# trig

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

prove.

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2. 👎
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1. 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

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2. 👎

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