Question 590939
cosx=3/5 0 < x <3pi/2 find sinx,cosx, and tanx by half angle identities
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{{{sin(x) = sqrt(1 - cos^2(x)) = 4/5}}}
Cosine is positive, --> Q1 & Q4 --> sine is +4/5 only
cos(x) is given
tan(x) = sin/cos = 4/3
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No half-angles are shown.  
If you want the half-angles, look at Wikipedia, it's covered well there.