Triangle - What is the length of the hypotenuse?












0












$begingroup$


Triangle ABC has a right angle at corner C. It has a height from C to a point D on side |AB|. If |CD|=5 and |AD|=7 then what is the length of the hypotenuse? (|AB|=?)



Correct Answer: 74/7



I have tried solving the question above by the help of the law of cosines and sines, pythagoras theorm and uniform triangles but without much success. I always tend to get to many unknown variables. Thanks in advance.










share|cite|improve this question









$endgroup$












  • $begingroup$
    right $triangle$-s ACD and ACB are similar, since they share angle a. Therefore, $|AD|/|CD| = |AC|/|BC|.
    $endgroup$
    – user2661923
    May 2 '18 at 23:17












  • $begingroup$
    @IGotAQuestion Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    $endgroup$
    – gimusi
    May 31 '18 at 19:49
















0












$begingroup$


Triangle ABC has a right angle at corner C. It has a height from C to a point D on side |AB|. If |CD|=5 and |AD|=7 then what is the length of the hypotenuse? (|AB|=?)



Correct Answer: 74/7



I have tried solving the question above by the help of the law of cosines and sines, pythagoras theorm and uniform triangles but without much success. I always tend to get to many unknown variables. Thanks in advance.










share|cite|improve this question









$endgroup$












  • $begingroup$
    right $triangle$-s ACD and ACB are similar, since they share angle a. Therefore, $|AD|/|CD| = |AC|/|BC|.
    $endgroup$
    – user2661923
    May 2 '18 at 23:17












  • $begingroup$
    @IGotAQuestion Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    $endgroup$
    – gimusi
    May 31 '18 at 19:49














0












0








0





$begingroup$


Triangle ABC has a right angle at corner C. It has a height from C to a point D on side |AB|. If |CD|=5 and |AD|=7 then what is the length of the hypotenuse? (|AB|=?)



Correct Answer: 74/7



I have tried solving the question above by the help of the law of cosines and sines, pythagoras theorm and uniform triangles but without much success. I always tend to get to many unknown variables. Thanks in advance.










share|cite|improve this question









$endgroup$




Triangle ABC has a right angle at corner C. It has a height from C to a point D on side |AB|. If |CD|=5 and |AD|=7 then what is the length of the hypotenuse? (|AB|=?)



Correct Answer: 74/7



I have tried solving the question above by the help of the law of cosines and sines, pythagoras theorm and uniform triangles but without much success. I always tend to get to many unknown variables. Thanks in advance.







geometry triangle






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked May 2 '18 at 23:06









IGotAQuestionIGotAQuestion

186




186












  • $begingroup$
    right $triangle$-s ACD and ACB are similar, since they share angle a. Therefore, $|AD|/|CD| = |AC|/|BC|.
    $endgroup$
    – user2661923
    May 2 '18 at 23:17












  • $begingroup$
    @IGotAQuestion Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    $endgroup$
    – gimusi
    May 31 '18 at 19:49


















  • $begingroup$
    right $triangle$-s ACD and ACB are similar, since they share angle a. Therefore, $|AD|/|CD| = |AC|/|BC|.
    $endgroup$
    – user2661923
    May 2 '18 at 23:17












  • $begingroup$
    @IGotAQuestion Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
    $endgroup$
    – gimusi
    May 31 '18 at 19:49
















$begingroup$
right $triangle$-s ACD and ACB are similar, since they share angle a. Therefore, $|AD|/|CD| = |AC|/|BC|.
$endgroup$
– user2661923
May 2 '18 at 23:17






$begingroup$
right $triangle$-s ACD and ACB are similar, since they share angle a. Therefore, $|AD|/|CD| = |AC|/|BC|.
$endgroup$
– user2661923
May 2 '18 at 23:17














$begingroup$
@IGotAQuestion Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
$endgroup$
– gimusi
May 31 '18 at 19:49




$begingroup$
@IGotAQuestion Please recall that if the OP is solved you can evaluate to accept an answer among the given, more details here meta.stackexchange.com/questions/5234/…
$endgroup$
– gimusi
May 31 '18 at 19:49










3 Answers
3






active

oldest

votes


















-1












$begingroup$

Draw a picture. You just need similar triangles. $ABC,ACD,$ and $CBD$ are similar. $frac {BD}{DC}=frac {CD}{AD}=frac 57$ so $BD=frac {25}7$ and $AB=AD+BD=7+frac {25}7=frac {74}7$






share|cite|improve this answer









$endgroup$





















    -1












    $begingroup$

    Remember that the height, $CD$, will be perpendicular to side $AB$. You can use Pythagorean Theorem to find length $AC$. Hint: Can you find the angle $angle CBA$? This will help you.






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
      $endgroup$
      – IGotAQuestion
      May 2 '18 at 23:20










    • $begingroup$
      The height (or altitude) of a triangle referenced to side $b$ must be perpendicular to $b$. You could also look at the other answers. There are probably many ways of solving it.
      $endgroup$
      – D.B.
      May 2 '18 at 23:23



















    -1












    $begingroup$

    HINT




    • make a sketch of the triangle

    • by Pytagoras find $AC$ from $AC^2=CD^2+AD^2$

    • then use similarity to find that $frac{AB}{AC}=frac{AC}{AD}$


    enter image description here






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
      $endgroup$
      – IGotAQuestion
      May 2 '18 at 23:22










    • $begingroup$
      it is true by definition of height, the height from a vertex is always perpendicular to the opposite side en.wikipedia.org/wiki/Altitude_(triangle)
      $endgroup$
      – gimusi
      May 2 '18 at 23:23












    • $begingroup$
      So if it says that a height is drawn from an angle, it is always perpendicular to the side it is drawn? Thanks!
      $endgroup$
      – IGotAQuestion
      May 2 '18 at 23:24










    • $begingroup$
      @IGotAQuestion Yes exactly, take a look to the link for the definition.
      $endgroup$
      – gimusi
      May 2 '18 at 23:25











    Your Answer





    StackExchange.ifUsing("editor", function () {
    return StackExchange.using("mathjaxEditing", function () {
    StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
    StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
    });
    });
    }, "mathjax-editing");

    StackExchange.ready(function() {
    var channelOptions = {
    tags: "".split(" "),
    id: "69"
    };
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function() {
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled) {
    StackExchange.using("snippets", function() {
    createEditor();
    });
    }
    else {
    createEditor();
    }
    });

    function createEditor() {
    StackExchange.prepareEditor({
    heartbeatType: 'answer',
    autoActivateHeartbeat: false,
    convertImagesToLinks: true,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: 10,
    bindNavPrevention: true,
    postfix: "",
    imageUploader: {
    brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
    contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
    allowUrls: true
    },
    noCode: true, onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    });


    }
    });














    draft saved

    draft discarded


















    StackExchange.ready(
    function () {
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2764090%2ftriangle-what-is-the-length-of-the-hypotenuse%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    -1












    $begingroup$

    Draw a picture. You just need similar triangles. $ABC,ACD,$ and $CBD$ are similar. $frac {BD}{DC}=frac {CD}{AD}=frac 57$ so $BD=frac {25}7$ and $AB=AD+BD=7+frac {25}7=frac {74}7$






    share|cite|improve this answer









    $endgroup$


















      -1












      $begingroup$

      Draw a picture. You just need similar triangles. $ABC,ACD,$ and $CBD$ are similar. $frac {BD}{DC}=frac {CD}{AD}=frac 57$ so $BD=frac {25}7$ and $AB=AD+BD=7+frac {25}7=frac {74}7$






      share|cite|improve this answer









      $endgroup$
















        -1












        -1








        -1





        $begingroup$

        Draw a picture. You just need similar triangles. $ABC,ACD,$ and $CBD$ are similar. $frac {BD}{DC}=frac {CD}{AD}=frac 57$ so $BD=frac {25}7$ and $AB=AD+BD=7+frac {25}7=frac {74}7$






        share|cite|improve this answer









        $endgroup$



        Draw a picture. You just need similar triangles. $ABC,ACD,$ and $CBD$ are similar. $frac {BD}{DC}=frac {CD}{AD}=frac 57$ so $BD=frac {25}7$ and $AB=AD+BD=7+frac {25}7=frac {74}7$







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered May 2 '18 at 23:15









        Ross MillikanRoss Millikan

        295k23198371




        295k23198371























            -1












            $begingroup$

            Remember that the height, $CD$, will be perpendicular to side $AB$. You can use Pythagorean Theorem to find length $AC$. Hint: Can you find the angle $angle CBA$? This will help you.






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:20










            • $begingroup$
              The height (or altitude) of a triangle referenced to side $b$ must be perpendicular to $b$. You could also look at the other answers. There are probably many ways of solving it.
              $endgroup$
              – D.B.
              May 2 '18 at 23:23
















            -1












            $begingroup$

            Remember that the height, $CD$, will be perpendicular to side $AB$. You can use Pythagorean Theorem to find length $AC$. Hint: Can you find the angle $angle CBA$? This will help you.






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:20










            • $begingroup$
              The height (or altitude) of a triangle referenced to side $b$ must be perpendicular to $b$. You could also look at the other answers. There are probably many ways of solving it.
              $endgroup$
              – D.B.
              May 2 '18 at 23:23














            -1












            -1








            -1





            $begingroup$

            Remember that the height, $CD$, will be perpendicular to side $AB$. You can use Pythagorean Theorem to find length $AC$. Hint: Can you find the angle $angle CBA$? This will help you.






            share|cite|improve this answer









            $endgroup$



            Remember that the height, $CD$, will be perpendicular to side $AB$. You can use Pythagorean Theorem to find length $AC$. Hint: Can you find the angle $angle CBA$? This will help you.







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered May 2 '18 at 23:16









            D.B.D.B.

            1,2708




            1,2708












            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:20










            • $begingroup$
              The height (or altitude) of a triangle referenced to side $b$ must be perpendicular to $b$. You could also look at the other answers. There are probably many ways of solving it.
              $endgroup$
              – D.B.
              May 2 '18 at 23:23


















            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:20










            • $begingroup$
              The height (or altitude) of a triangle referenced to side $b$ must be perpendicular to $b$. You could also look at the other answers. There are probably many ways of solving it.
              $endgroup$
              – D.B.
              May 2 '18 at 23:23
















            $begingroup$
            How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
            $endgroup$
            – IGotAQuestion
            May 2 '18 at 23:20




            $begingroup$
            How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
            $endgroup$
            – IGotAQuestion
            May 2 '18 at 23:20












            $begingroup$
            The height (or altitude) of a triangle referenced to side $b$ must be perpendicular to $b$. You could also look at the other answers. There are probably many ways of solving it.
            $endgroup$
            – D.B.
            May 2 '18 at 23:23




            $begingroup$
            The height (or altitude) of a triangle referenced to side $b$ must be perpendicular to $b$. You could also look at the other answers. There are probably many ways of solving it.
            $endgroup$
            – D.B.
            May 2 '18 at 23:23











            -1












            $begingroup$

            HINT




            • make a sketch of the triangle

            • by Pytagoras find $AC$ from $AC^2=CD^2+AD^2$

            • then use similarity to find that $frac{AB}{AC}=frac{AC}{AD}$


            enter image description here






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:22










            • $begingroup$
              it is true by definition of height, the height from a vertex is always perpendicular to the opposite side en.wikipedia.org/wiki/Altitude_(triangle)
              $endgroup$
              – gimusi
              May 2 '18 at 23:23












            • $begingroup$
              So if it says that a height is drawn from an angle, it is always perpendicular to the side it is drawn? Thanks!
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:24










            • $begingroup$
              @IGotAQuestion Yes exactly, take a look to the link for the definition.
              $endgroup$
              – gimusi
              May 2 '18 at 23:25
















            -1












            $begingroup$

            HINT




            • make a sketch of the triangle

            • by Pytagoras find $AC$ from $AC^2=CD^2+AD^2$

            • then use similarity to find that $frac{AB}{AC}=frac{AC}{AD}$


            enter image description here






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:22










            • $begingroup$
              it is true by definition of height, the height from a vertex is always perpendicular to the opposite side en.wikipedia.org/wiki/Altitude_(triangle)
              $endgroup$
              – gimusi
              May 2 '18 at 23:23












            • $begingroup$
              So if it says that a height is drawn from an angle, it is always perpendicular to the side it is drawn? Thanks!
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:24










            • $begingroup$
              @IGotAQuestion Yes exactly, take a look to the link for the definition.
              $endgroup$
              – gimusi
              May 2 '18 at 23:25














            -1












            -1








            -1





            $begingroup$

            HINT




            • make a sketch of the triangle

            • by Pytagoras find $AC$ from $AC^2=CD^2+AD^2$

            • then use similarity to find that $frac{AB}{AC}=frac{AC}{AD}$


            enter image description here






            share|cite|improve this answer









            $endgroup$



            HINT




            • make a sketch of the triangle

            • by Pytagoras find $AC$ from $AC^2=CD^2+AD^2$

            • then use similarity to find that $frac{AB}{AC}=frac{AC}{AD}$


            enter image description here







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered May 2 '18 at 23:19









            gimusigimusi

            92.8k84494




            92.8k84494












            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:22










            • $begingroup$
              it is true by definition of height, the height from a vertex is always perpendicular to the opposite side en.wikipedia.org/wiki/Altitude_(triangle)
              $endgroup$
              – gimusi
              May 2 '18 at 23:23












            • $begingroup$
              So if it says that a height is drawn from an angle, it is always perpendicular to the side it is drawn? Thanks!
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:24










            • $begingroup$
              @IGotAQuestion Yes exactly, take a look to the link for the definition.
              $endgroup$
              – gimusi
              May 2 '18 at 23:25


















            • $begingroup$
              How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:22










            • $begingroup$
              it is true by definition of height, the height from a vertex is always perpendicular to the opposite side en.wikipedia.org/wiki/Altitude_(triangle)
              $endgroup$
              – gimusi
              May 2 '18 at 23:23












            • $begingroup$
              So if it says that a height is drawn from an angle, it is always perpendicular to the side it is drawn? Thanks!
              $endgroup$
              – IGotAQuestion
              May 2 '18 at 23:24










            • $begingroup$
              @IGotAQuestion Yes exactly, take a look to the link for the definition.
              $endgroup$
              – gimusi
              May 2 '18 at 23:25
















            $begingroup$
            How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
            $endgroup$
            – IGotAQuestion
            May 2 '18 at 23:22




            $begingroup$
            How can you know that the height CD will be perpendicular to AB? It seems to me to be an anjustified assumption.
            $endgroup$
            – IGotAQuestion
            May 2 '18 at 23:22












            $begingroup$
            it is true by definition of height, the height from a vertex is always perpendicular to the opposite side en.wikipedia.org/wiki/Altitude_(triangle)
            $endgroup$
            – gimusi
            May 2 '18 at 23:23






            $begingroup$
            it is true by definition of height, the height from a vertex is always perpendicular to the opposite side en.wikipedia.org/wiki/Altitude_(triangle)
            $endgroup$
            – gimusi
            May 2 '18 at 23:23














            $begingroup$
            So if it says that a height is drawn from an angle, it is always perpendicular to the side it is drawn? Thanks!
            $endgroup$
            – IGotAQuestion
            May 2 '18 at 23:24




            $begingroup$
            So if it says that a height is drawn from an angle, it is always perpendicular to the side it is drawn? Thanks!
            $endgroup$
            – IGotAQuestion
            May 2 '18 at 23:24












            $begingroup$
            @IGotAQuestion Yes exactly, take a look to the link for the definition.
            $endgroup$
            – gimusi
            May 2 '18 at 23:25




            $begingroup$
            @IGotAQuestion Yes exactly, take a look to the link for the definition.
            $endgroup$
            – gimusi
            May 2 '18 at 23:25


















            draft saved

            draft discarded




















































            Thanks for contributing an answer to Mathematics Stack Exchange!


            • Please be sure to answer the question. Provide details and share your research!

            But avoid



            • Asking for help, clarification, or responding to other answers.

            • Making statements based on opinion; back them up with references or personal experience.


            Use MathJax to format equations. MathJax reference.


            To learn more, see our tips on writing great answers.




            draft saved


            draft discarded














            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f2764090%2ftriangle-what-is-the-length-of-the-hypotenuse%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown





















































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown

































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown







            Popular posts from this blog

            Human spaceflight

            Can not write log (Is /dev/pts mounted?) - openpty in Ubuntu-on-Windows?

            File:DeusFollowingSea.jpg