Question 669984
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Hi,
(cos(t))^2=1/4
cos(t)= ± 1/2
 t = (1/3)pi, (5/3)pi, (2/3)pi, (4/3)pi
Thought the following (cosx, sinx) summary would help You in Your studies
<img src="http://www.math.ucsd.edu/~jarmel/math4c/Unit_Circle_Angles.png">