题目
已知θ为第四象限角,tan(π+θ)=-2.
(1)化简
(1)化简
tan(π−θ)sin(
| ||
cos(−θ−π)sin(−5π+θ) |
提问时间:2021-04-01
答案
(1)
=
=−
=−
;
(2)∵tan(π+θ)=-2
∴tanθ=
=-2即sinθ=-2cosθ
又sin2θ+cos2θ=1∴cosθ=±
tan(π−θ)sin(
| ||
cos(−θ−π)sin(−5π+θ) |
−tanθcosθ |
−cosθ(−sinθ) |
=−
tanθ |
sinθ |
1 |
cosθ |
(2)∵tan(π+θ)=-2
∴tanθ=
sinθ |
cosθ |
又sin2θ+cos2θ=1∴cosθ=±