听雨-落荷
幼苗
共回答了15个问题采纳率：93.3% 举报
1+sin4Θ-cos4Θ=2sin2θcos2θ+2(sin2θ)^2=2sin2θ(sin2θ+cos2θ)
1+sin4Θ+cos4Θ=2sin2θcos2θ+2(cos2θ)^2=2cos2θ(sin2θ+cos2θ)
∴1+sin4Θ-cos4Θ/1+sin4Θ+cos4Θ
=tan2θ
= - cot2(θ+π/4)
= - (1-tan(θ+π/4)^2)/(2tan(θ+π/4)
=(3^2-1)/(2×3)
=4/3
1年前
6
