求两条式子的值arccot[cot(-1/2)]arccot[cot(-1/2)]cos(2arctan5)

题目详情

求两条式子的值 arccot[cot(-1/2)]
arccot[cot(-1/2)]
cos(2arctan5)

▼优质解答

答案和解析

1. arccot[cot(-1/2)] =arccot[-cot(1/2)] =π-arccot[cot(1/2)] = π- 1/2 2. cos(2arctan5) 设arctan5=α ,则tanα=5, α∈（0,π/2）则 cos(...

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