a-maths~~~~~~~

2007-10-16 1:39 am

回答 (1)

2007-10-16 4:41 am
✔ 最佳答案
(1) L.H.S. = [1–sec(π/2–θ)–cot (2π-θ)]/[1+sec(3π/2+θ)+cot(π-θ)]
=(1-cscθ+cotθ)/(1+cscθ-cotθ)
=(1-cscθ+cotθ)(1+cscθ+cotθ)/(1+cscθ-cotθ)(1+cscθ+cotθ)
=[(1+cotθ)2-csc2θ]/[(1+cscθ)2-cot2θ] [Since 1+cot2θ=csc2θ]
=[(1+cotθ)2- (1+cot2θ)]/(1+2cscθ+csc2θ-csc2θ+1)
=(1+2cotθ+cot2θ-cot2θ-1)/2(cscθ+1)
= cotθ/ ( 1 + cscθ)
=R.H.S.
(2)L.H.S. = [1+cos(3π/2+θ)][1+csc(5π/2-θ)]/[1- cos(π-θ)][1-csc(-θ)]
=(1+sinθ)(1+secθ)/(1+cosθ)(1+cscθ)
=(sinθcosθ+sin2θcosθ)(sinθcosθ+sinθ)/(sinθcosθ+sin2θcosθ)(sinθcosθ)(sinθcosθ+cosθ)
=sin2θcosθ(1+sinθ)(1+cosθ)/sinθcos2θ(1+sinθ)(1+cosθ)
=sinθ/cosθ
=tanθ
R.H.S.=-cot(θ-3π/2)
=cot(3π/2-θ)
=tan(θ-π)
=tanθ
=L.H.S.
參考: My Maths Knowledge


收錄日期: 2021-04-23 20:35:39
原文連結 [永久失效]:
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