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Math Help - [SOLVED] No idea about this. (sine/cosine)

  1. #1
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    [SOLVED] No idea about this. (sine/cosine)

    I have no idea what to do. Our professor didnt teach us this. help please.

    Find the value of if is in the second quadrant and



    Find the value of if is in the third quadrant and




    Find the value of if and .
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  2. #2
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    Quote Originally Posted by lsnyder View Post
    I have no idea what to do. Our professor didnt teach us this. help please.

    Find the value of if is in the second quadrant and

    Draw a triangle in the second quadrant and label the sides . You will get a negative value for cos .

    Find the value of if is in the third quadrant and

    Same thing . Draw a triangle in the 3rd quadrant . Sin a will be negative .



    Find the value of if and
    Given cos a is negative and sin a is postitive . Thus the angle will be in the 2nd quadrant . Draw a triangle in the second quadrant .

    .
    See quote
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  3. #3
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    huh?
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  4. #4
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    Quote Originally Posted by lsnyder View Post
    huh?
    That tells me that you are still in doubt ..

    (a) Given sin a = 24/25 and a is in the second quadrant . Draw a triangle with opposite side 24 and hypothenus 25 , so the adjacent side will be -7 .

    cos a is negative here = -7/25

    (b) Can u try this one .

    (c) Given cos a is negative and sin a is postitive . Thus the angle will be in the 2nd quadrant . sin a =24/25

    THis is the same as (a) .
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  5. #5
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    oh, i get it.
    Thank you so much.


    (b) was was -3/5
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  6. #6
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    Quote Originally Posted by lsnyder View Post
    oh, i get it.
    Thank you so much.


    (b) was was -3/5
    You are right .
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