题目
求解一道化简题
sin(2A-B)/sinA-2cos(A-B)
答案解析
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举报
=sin[a+(a-b)]/sina-2cos(a-b)
=[sinAcos(a-b)+cosAsin(a-b)]/sina-2cos(a-b)
=-cos(a-b)+cosAsin(a-b)/sina
=[sin(a-b)cosA-cos(A-B)siaA]/sinA
=sin(a-b-a)/sinA
=-sinB/sinA
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