Thanks
更新1:
tan(θ+ϕ) = tanθ+tanϕ / 1-tanθ.tanϕ
trigonometry prove
回答 (3)
2010-07-18 7:40 pm
✔ 最佳答案
Prove tan(θ+ϕ) = tanθ+tanϕ / 1-tanθ.tanϕ?2010-07-18 11:40:29 補充：
As follows:
圖片參考：http://i707.photobucket.com/albums/ww74/stevieg90/01-130.jpg
2010-07-18 9:56 pm
trigonometry prove
Prove that Cot^2θ－Cos^2θ=Cot^2θ Cos^2θ
Sol
Cos^2 θ +Cot^2 θ Cos^2 θ
=Cos^2 θ (1+Cot^2 θ )
=Cos^2 θ (1+Cos^2 θ /Sin^2 θ )
=Cos^2 θ/Sin^2 θ
=Cot^2 θ
So
Cot^2θ－Cos^2θ=Cot^2θ Cos^2θ
Prove that Cot^2θ－Cos^2θ=Cot^2θ Cos^2θ
Sol
Cos^2 θ +Cot^2 θ Cos^2 θ
=Cos^2 θ (1+Cot^2 θ )
=Cos^2 θ (1+Cos^2 θ /Sin^2 θ )
=Cos^2 θ/Sin^2 θ
=Cot^2 θ
So
Cot^2θ－Cos^2θ=Cot^2θ Cos^2θ
2010-07-18 7:29 pm
yes, that is another question.
thanks
thanks
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