Find value of a with given angle












-1












$begingroup$


The equations of the line $L$ and the plane $Pi$ are as follows:



$$
L: qquad x-5=-(y+1); z = 4
$$

$$
Pi : qquad alpha x + z = 5alpha +4
$$

where $alpha$ is a constant.



If the angle between the line $L$ and $Pi$ is $pi/6$, what is the value of $alpha$?



There are two answers, one positive and negative, but the answers I got is only negative. Any help please. Thanking you guys in advanced :D










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$endgroup$








  • 2




    $begingroup$
    can you include your working?
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:02










  • $begingroup$
    @SiongThyeGoh ibb.co/6t3PkD1 sorry the answer i got was a negative
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:06






  • 1




    $begingroup$
    please learn mathjax and type out your attempt in the question.
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:23










  • $begingroup$
    will do :D thanks
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:29
















-1












$begingroup$


The equations of the line $L$ and the plane $Pi$ are as follows:



$$
L: qquad x-5=-(y+1); z = 4
$$

$$
Pi : qquad alpha x + z = 5alpha +4
$$

where $alpha$ is a constant.



If the angle between the line $L$ and $Pi$ is $pi/6$, what is the value of $alpha$?



There are two answers, one positive and negative, but the answers I got is only negative. Any help please. Thanking you guys in advanced :D










share|cite|improve this question











$endgroup$








  • 2




    $begingroup$
    can you include your working?
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:02










  • $begingroup$
    @SiongThyeGoh ibb.co/6t3PkD1 sorry the answer i got was a negative
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:06






  • 1




    $begingroup$
    please learn mathjax and type out your attempt in the question.
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:23










  • $begingroup$
    will do :D thanks
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:29














-1












-1








-1





$begingroup$


The equations of the line $L$ and the plane $Pi$ are as follows:



$$
L: qquad x-5=-(y+1); z = 4
$$

$$
Pi : qquad alpha x + z = 5alpha +4
$$

where $alpha$ is a constant.



If the angle between the line $L$ and $Pi$ is $pi/6$, what is the value of $alpha$?



There are two answers, one positive and negative, but the answers I got is only negative. Any help please. Thanking you guys in advanced :D










share|cite|improve this question











$endgroup$




The equations of the line $L$ and the plane $Pi$ are as follows:



$$
L: qquad x-5=-(y+1); z = 4
$$

$$
Pi : qquad alpha x + z = 5alpha +4
$$

where $alpha$ is a constant.



If the angle between the line $L$ and $Pi$ is $pi/6$, what is the value of $alpha$?



There are two answers, one positive and negative, but the answers I got is only negative. Any help please. Thanking you guys in advanced :D







geometry






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share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 17 at 13:15









idriskameni

749321




749321










asked Jan 17 at 13:00









Master Irfan ElaheeMaster Irfan Elahee

13




13








  • 2




    $begingroup$
    can you include your working?
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:02










  • $begingroup$
    @SiongThyeGoh ibb.co/6t3PkD1 sorry the answer i got was a negative
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:06






  • 1




    $begingroup$
    please learn mathjax and type out your attempt in the question.
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:23










  • $begingroup$
    will do :D thanks
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:29














  • 2




    $begingroup$
    can you include your working?
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:02










  • $begingroup$
    @SiongThyeGoh ibb.co/6t3PkD1 sorry the answer i got was a negative
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:06






  • 1




    $begingroup$
    please learn mathjax and type out your attempt in the question.
    $endgroup$
    – Siong Thye Goh
    Jan 17 at 13:23










  • $begingroup$
    will do :D thanks
    $endgroup$
    – Master Irfan Elahee
    Jan 17 at 13:29








2




2




$begingroup$
can you include your working?
$endgroup$
– Siong Thye Goh
Jan 17 at 13:02




$begingroup$
can you include your working?
$endgroup$
– Siong Thye Goh
Jan 17 at 13:02












$begingroup$
@SiongThyeGoh ibb.co/6t3PkD1 sorry the answer i got was a negative
$endgroup$
– Master Irfan Elahee
Jan 17 at 13:06




$begingroup$
@SiongThyeGoh ibb.co/6t3PkD1 sorry the answer i got was a negative
$endgroup$
– Master Irfan Elahee
Jan 17 at 13:06




1




1




$begingroup$
please learn mathjax and type out your attempt in the question.
$endgroup$
– Siong Thye Goh
Jan 17 at 13:23




$begingroup$
please learn mathjax and type out your attempt in the question.
$endgroup$
– Siong Thye Goh
Jan 17 at 13:23












$begingroup$
will do :D thanks
$endgroup$
– Master Irfan Elahee
Jan 17 at 13:29




$begingroup$
will do :D thanks
$endgroup$
– Master Irfan Elahee
Jan 17 at 13:29










1 Answer
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$begingroup$

$$L:begin{pmatrix} x \ y \ zend{pmatrix}=begin{pmatrix} 5 \ -1 \ 4end{pmatrix}+ lambda begin{pmatrix}1 \ -1\ 0 end{pmatrix}$$



$$frac{|langle(1,-1,0),(alpha, 0,1)rangle|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



$$frac{|alpha|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



Hopefully you can solve for $alpha$ to obtain one positive and one negative value of $alpha$ from here.






share|cite|improve this answer









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    1 Answer
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    0












    $begingroup$

    $$L:begin{pmatrix} x \ y \ zend{pmatrix}=begin{pmatrix} 5 \ -1 \ 4end{pmatrix}+ lambda begin{pmatrix}1 \ -1\ 0 end{pmatrix}$$



    $$frac{|langle(1,-1,0),(alpha, 0,1)rangle|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



    $$frac{|alpha|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



    Hopefully you can solve for $alpha$ to obtain one positive and one negative value of $alpha$ from here.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      $$L:begin{pmatrix} x \ y \ zend{pmatrix}=begin{pmatrix} 5 \ -1 \ 4end{pmatrix}+ lambda begin{pmatrix}1 \ -1\ 0 end{pmatrix}$$



      $$frac{|langle(1,-1,0),(alpha, 0,1)rangle|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



      $$frac{|alpha|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



      Hopefully you can solve for $alpha$ to obtain one positive and one negative value of $alpha$ from here.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        $$L:begin{pmatrix} x \ y \ zend{pmatrix}=begin{pmatrix} 5 \ -1 \ 4end{pmatrix}+ lambda begin{pmatrix}1 \ -1\ 0 end{pmatrix}$$



        $$frac{|langle(1,-1,0),(alpha, 0,1)rangle|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



        $$frac{|alpha|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



        Hopefully you can solve for $alpha$ to obtain one positive and one negative value of $alpha$ from here.






        share|cite|improve this answer









        $endgroup$



        $$L:begin{pmatrix} x \ y \ zend{pmatrix}=begin{pmatrix} 5 \ -1 \ 4end{pmatrix}+ lambda begin{pmatrix}1 \ -1\ 0 end{pmatrix}$$



        $$frac{|langle(1,-1,0),(alpha, 0,1)rangle|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



        $$frac{|alpha|}{sqrt2cdot sqrt{alpha^2+1}}=cosfrac{pi}6$$



        Hopefully you can solve for $alpha$ to obtain one positive and one negative value of $alpha$ from here.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 17 at 13:20









        Siong Thye GohSiong Thye Goh

        104k1468120




        104k1468120






























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