SOLUTION: Simplify the following: sin (90° + x) sin (180° + x) + cos (90° + x) cos (180° – x)

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Question 476923: Simplify the following:
sin (90° + x) sin (180° + x) + cos (90° + x) cos (180° – x)

Answer by robertb(5830)   (Show Source): You can put this solution on YOUR website!




==>sin (90° + x) sin (180° + x) + cos (90° + x) cos (180° – x) =
cosx*-sinx + -sinx*-cosx = -sinx*cosx + sinx*cosx = 0.

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