Question 545805
cos(arcsin(-3/5))
arcsin(-3/5) is a reference angle whose sin=-3/5 in quadrant IV where sin<0 and cos>0.
note: arcsin(-3/5) could also be in quadrant III where sin is also<0, but its domain is: [-&#960;/2, &#960;/2]
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cos of this same reference angle=4/5
Therefore, cos(arcsin(-3/5))=4/5