贝贝雅
幼苗
共回答了11个问题采纳率:90.9% 举报
1、∵sin(θ+kπ)=-2cos(θ+kπ),k∈Z
则sin(θ+kπ)/cos(θ+kπ)=-2,k∈Z
∴tan(θ+kπ)=-2,k∈Z
∴tanθ=-2
2、原式=1+2sinθ*cosθ/(sin²θ-cos²θ)
=1+sin2θ/(-cos2θ)
=1-tan2θ
=1-2tanθ/(1-tan²θ)
=1-2×(-2)/[1-(-2)²]
=-1/3
3、原式=sin²θ+2sinθ*cosθ+2
=sinθ*cosθ*(tanθ+2)+2
=sinθ*cosθ*(-2+2)+2
=2
=sinθ*()
1年前
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