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Math Help - Inverse Trig

  1. #1
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    Inverse Trig

    Ok, so I have taken this class before, but this section just lost me...

    Find the other two trig functions if x lies in the specified interval:
    sinx=(3/5) X=[π/2, π]

    Thank you
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  2. #2
    MHF Contributor ebaines's Avatar
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    Remember that sine is defined as the ratio of "opposite" over "hypotenuse." To find the "other two" trig functions - I assume you mean cosine and tangent - you will need to determine the length of the missing third side of the triangle, which is the "adjacent" side. Simply use the Pythagorian theorem: adjacent =sqrt(5^2 - 3^2) = 4. So now you know that cosine = adjacent over hypotenuse = 4/5, and tangent = opposite/adjacent = 3/4. BUT... you need to determine whether the adjacent is considered plus 4 or negative 4. You are told that the angle is between pi/2 and pi - that's the 2nd quadrant, where sines are positive and both cosines and tangents are negative.
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