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问题: 关于两角和与差的化简..

化简:sinA+sin(A+2派/3)+cos(A+5派/6)

解答:

sinA+sin[派-(A+2派/3)])+sin[派/2 -(A+5派/6)]
=sinA-[sin(A-派/3) +sin(A+派/3)]
=sinA -2sinAcos( -派/3)
=sinA-sinA
=0