Question 543342
evaluate the following: 
sin^-1 (Cos 2pi/3)
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Cos (2&#960;/3) =-1/2 ( reference angle of &#960;/3 in quadrant II where cos<0
sin^-1 (Cos 2pi/3)=sin^-1 (-1/2)=-&#960;/6
note: domain of sin^-1 is [-&#960;/2,&#960;/2]