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Math Help - Trig Question

  1. #1
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    Trig Question

    Can anyone please help on this.

    Don't know what I am meant to do and how to work it out.

    Thanks

    I have attached the problem.

    Trig Question-quest-9.jpg
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Braindead View Post
    Can anyone please help on this.

    Don't know what I am meant to do and how to work it out.

    Thanks

    I have attached the problem.

    Click image for larger version. 

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    note that the magnitude of the vertical side is \sin \theta and the magnitude of the base is \cos \theta by SOHCAHTOA.

    Now apply Pythagoras' theorem
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  3. #3
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    Thanks.

    But I don't know what the question is asking me to do.
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Braindead View Post
    Thanks.

    But I don't know what the question is asking me to do.
    it is asking you to prove that \sin^2 \theta + \cos^2 \theta = 1

    just do what i said, you will get there
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  5. #5
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    Sorry I'm a bit thicker than most.

    I don't actually understand what He means by this part of the question.

    Trig Question-7.jpg

    I can understand what the first part is that sin(x)^2 + cos(x)^2 = 1

    But what is He trying to tell me to do.

    Thanks for your time.
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  6. #6
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    Quote Originally Posted by Braindead View Post
    Sorry I'm a bit thicker than most.

    I don't actually understand what He means by this part of the question.

    Click image for larger version. 

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    I can understand what the first part is that sin(x)^2 + cos(x)^2 = 1

    But what is He trying to tell me to do.

    Thanks for your time.
    The triangle you have been given can only be constructed if the angle \theta is between 0 and 90 degrees.

    Call the length of the horizontal "leg" of the triangle a. Call the length of the vertical "leg" of the triangle b. In terms of the angle \theta, what are the values for a and b?

    Once you have that, notice that you have a right triangle. Apply the Pythagorean Theorem.

    -Dan
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  7. #7
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    Quote Originally Posted by Braindead View Post
    Sorry I'm a bit thicker than most.

    I don't actually understand what He means by this part of the question.

    Click image for larger version. 

Name:	7.jpg 
Views:	41 
Size:	2.4 KB 
ID:	4076

    I can understand what the first part is that sin(x)^2 + cos(x)^2 = 1

    But what is He trying to tell me to do.

    Thanks for your time.
    He means for any angle theta between 0 degree and 90 degrees.
    0 and 90 degrees are not included because with theta as zero degree or 90 degrees, you have no right triangle. There is already one 90-degree angle in the shown right triangle. The 3 interior angles are supposed to add up only to 180 degrees.

    To picture the 0deg < theta < 90deg more, first make the theta in the figure approximately or about 5 degrees only, or 10 degrees, or dependending on how small it can get in your sketch.
    The resulting triangle looks very flat, yet, still it is a right triangle and
    sin^2(5deg) +cos^2(5deg) = 1 still.

    Then make theta about 80 degrees. The resulting right triangle looks like a a tall pole. Yet, still, sin^2(80deg) +cos^2(80deg) = 1.

    Get your calculator and check those.
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  8. #8
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    Thanks to all of you. I worked it out finally. I wish I had $1.00 for every hour I spent on it.

    Thanks a lot.
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