Posted by **Spencer** on Tuesday, January 20, 2009 at 7:34pm.

(cotxsec2x - cotx)/ (sinxtanx + cosx) = sinx

prove.

i keep getting (if i start from the left side) = cosx instead of sinx please help!

- trig -
**Reiny**, Tuesday, January 20, 2009 at 9:25pm
first of all you should have typed it correctly as

(cotxsec^2 x - cotx)/ (sinxtanx + cosx) = sinx

I read that first part as sec(2x), and wasted about 10 minutes trying to prove that.

so...

LS = [cotx(1/cos^2x - 1)]/[sin^2x/cosx + cosx]

= [cotx(1 - cos^2x)/cos^2x]/[(sin^x + cos^2x)cosx]

= [cotx(sin^2x/cos^2x)]/[1/cosx]

= [sinx/cosx]/[1/cosx]

= sinx

= RS

## Answer this Question

## Related Questions

- Trigonometry. - ( tanx/1-cotx )+ (cotx/1-tanx)= (1+secxcscx) Good one! ...
- trigonometry - can i use factoring to simplify this trig identity? the problem ...
- Trig........ - I need to prove that the following is true. Thanks (cosx / 1-sinx...
- Pre-calc - prove the identity: (cosx)(tanx + sinx cotx)=sinx+cos(squared)x i ...
- Pre-Calc - Trigonometric Identities Prove: (tanx + secx -1)/(tanx - secx + 1)= ...
- Math - Verify the identity . (cscX-cotX)^2=1-cosX/1+cosX _______ sorry i cant ...
- Math - Im really struggling with these proving identities problems can somebody ...
- Precalculus/Trig - I can't seem to prove these trig identities and would really ...
- trig - express this in sinx (1/ cscx + cotx )+ (1/cscx- cotx) i got 2sinx is ...
- Trig - Verify the identity: tanx(cos2x) = sin2x - tanx Left Side = (sinx/cosx)(...

More Related Questions