若tan(π+x)=2,求:(1)4sinx-2cosx5cosx+3sinx;(2)sinxcosx1+cos2x.-数学

题目简介

若tan(π+x)=2,求:(1)4sinx-2cosx5cosx+3sinx;(2)sinxcosx1+cos2x.-数学

题目详情

若tan(π+x)=2,求:
(1)
4sinx-2cosx
5cosx+3sinx

(2)
sinxcosx
1+cos2x
题型:解答题难度:中档来源:不详

答案

tan(π+x)=2,tanx=2,
(1)class="stub"4sinx-2cosx
5cosx+3sinx
=class="stub"4tanx-2
5+3tanx
=class="stub"4×2-2
5+3×2
=class="stub"5
7

(2)class="stub"sinxcosx
1+cos2x
=class="stub"tanx
2+tan2x
=class="stub"2
2+2×2
=class="stub"1
3

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