Simplification of sin ^ 2 (X-30) + sin ^ 2 (x + 30) - Sin ^ 2 (x)

Simplification of sin ^ 2 (X-30) + sin ^ 2 (x + 30) - Sin ^ 2 (x)

sin^2(x-30)+sin^2(x+30)-sin^2(x)
=(1-cos(2x-60))/2+(1-cos(2x+60))/2-sin^2x
=1-1/2[cos(2x-60)+cos(2x+60)]-sin^2x
=-1/2[cos2xcos60+sin2xsin60+cos2xcos60-sin2xsin60]+cos^2
=-1/2[2×1\2cos2x]+cos^2
=cos^2-1/2cos2x
=（1+cos2x）\2-1/2cos2x
=The simplification of 1 / 2 general trigonometric functions is mostly evaluated, and most of them get exact numbers

Is trigonometric function right? Sin (- α - 3 / 2 π) sin (3 / 2 π - α) Tan ^ 2 (2 π - α) is a molecule
Cos (π / 2 - α) cos (π / 2 + α) cot (π - α) is the denominator, and the last is - Tan ^ 5 α, right?

Incorrect, because: {sin (- α - 3 / 2 π) sin (3 / 2 π - α) Tan ^ 2 (2 π - α)} / {cos (π / 2 - α) cos (π / 2 + α) cot (π - α)} = {sin (π / 2 - α) sin (3 / 2 π - α) Tan ^ 2 (2 π - α)} / {cos (π / 2 - α) cos (π / 2 + α) cot (π - α)} = {cos α (- cos α) Tan