1.Prove that tan^2ɵ- sin^2ɵ= tan^2ɵsin^2ɵ is an identity.
2.Prove that (1/tan^2ɵ+1) + sin^2ɵ = 1 is an identity.
3.Prove that (cosɵ/tanɵ)/sinɵ= 1
4.Prove that (cosɵ/ tanɵ)+ sinɵ= 1/sinɵ
F3.math
2008-04-17 4:10 am
回答 (1)
2008-04-17 8:12 am
✔ 最佳答案
I use x instead of ɵ1
tan^2x-sin^2x
=sin^2x(1/cos^2x-1)
=sin^2x(1-cos^2x)/cos^2x
=tan^2xsin^2x
2
(1/tan^2x+1)+sin^2x
=1/[(sin^2x/cos^2x)+1]+sin^2x
=cos^2x+sin^2x
=1
3
The original question is wrong, I think the question is
(cosxtanx)/sinx
=(cosx)(sinx/cosx)(1/sinx)
=1
4
(cosx/tanx)+sinx
=cosx(cosx/sinx)+sinx
=(cos^2x+sin^2x)/sinx
=1/sinx
收錄日期: 2021-04-25 16:58:13
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