Question 891837
please help me these problems 
1) sin π/2=cos 
2π 
non of these
π 
π /2
3π/3 
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sin(pi/2) = sin(90 deg) = 1
Find the angle whose cosine = 1 (called arccos(1), acos(1), invcos(1) )
In degs, it's 0, 180, 360, etc
In radians, it's 0, pi, 2pi, etc
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Do the others the same way.