Thomas E. answered 04/11/16
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Use the Unit circle for exact values of the trig ratios of 30, 45 and 60.
sin2 30 + cos2 30 = (1/2)2 + (sqrt 3/2)2 = 1/4 + 3/4 = 1 (sin2 x + cos2 x always equals 1
(cos 45)(sin 30)(cot 60) = (sqrt2/2)(1/2)(sqrt3/3) = sqrt6/12