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Math Help - sine and cosine functions

  1. #1
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    Question sine and cosine functions

    Given that Q is approximately (0.259,0.966) is a point on the unit circle with angle 75 degrees, estimate sin 285 degrees and cos 285 degrees without a calculator.

    I am stuck!
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  2. #2
    Super Member 11rdc11's Avatar
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    Quote Originally Posted by Kate182 View Post
    Given that Q is approximately (0.259,0.966) is a point on the unit circle with angle 75 degrees, estimate sin 285 degrees and cos 285 degrees without a calculator.

    I am stuck!
    Ok use a reference angle for 285. So the reference angle would be 75.

    Now use sum identity formula

    \cos{(45 +30)}=\cos{45}\cos{30}-\sin{45}\sin{30}
    Last edited by 11rdc11; October 27th 2008 at 03:47 PM.
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