sin(-19π/6)/(sec4π/3)+tan7π/4=

题目详情

▼优质解答

答案和解析

原式=sin(-19π/6+4π)cos(π+π/3)+tan(π+3/4π)
=-sin(5π/6)cos(π/3)+tan(3π/4)
=-1/2×1/2-1
=-5/4

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