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  1. #1
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    Question.

    The question is, Does there exist an angle theta with the function values COS theta=.6 and SIN theta=-.8.....could someone explain this to me. Not really sure what is meant by the question.
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  2. #2
    No one in Particular VonNemo19's Avatar
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    Quote Originally Posted by Brndo4u View Post
    The question is, Does there exist an angle theta with the function values COS theta=.6 and SIN theta=-.8.....could someone explain this to me. Not really sure what is meant by the question.
    .6=\frac{6}{10}=\frac{3}{5} implies a 345 triangle


    .8=\frac{8}{10}=\frac{4}{5} implies a 345 triangle

    Can you see where I'm going?
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  3. #3
    Super Member bigwave's Avatar
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    Cool

    since cos\theta = \frac{3}{5} and sin\theta = -\frac{4}{5}

    that means the hyp is 5 for both functions

    since cos\theta is postive it must be in Q-I or Q-4

    since sin\theta is negative it must be in Q-3 or Q-4

    so \theta exists and is in Q-4

    hope this helps
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  4. #4
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    Quote Originally Posted by Brndo4u View Post
    The question is, Does there exist an angle theta with the function values COS theta=.6 and SIN theta=-.8.....could someone explain this to me. Not really sure what is meant by the question.
    From the Pythagorean Identity:

    \cos^2{\theta} + \sin^2{\theta} = 1.


    So check what (0.6)^2 + (-0.8)^2 equals.

    If it equals 1 then there must exist some \theta that holds for your conditions.
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  5. #5
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    Yes.... thanks
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