若tanθ+1tanθ=8,则sin2θ=()A.15B.14C.13D.12-数学

题目简介

若tanθ+1tanθ=8,则sin2θ=()A.15B.14C.13D.12-数学

题目详情

tanθ+
1
tanθ
=8
,则sin2θ=(  )
A.
1
5
B.
1
4
C.
1
3
D.
1
2
题型:单选题难度:偏易来源:不详

答案

tanθ+class="stub"1
tanθ
=8
,则
sin2θ=2sinθcosθ=class="stub"2sinθcosθ
sin2θ+cos2θ
=class="stub"2tanθ
tan2θ+1
=class="stub"2
tanθ+class="stub"1
tanθ
=class="stub"2
8
=class="stub"1
4

故选B

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