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## A dump of our free Chat sessions, in case it is useful. It excludes white boards used during paid sessions.

student : hey its an identity.
student : (1-2sin^2x)/sinxcosx = cotx-tanx
tutorsd6 : 1 - 2sin^2 x = cos 2x
student : how did you get the cos2x on the right side?
tutorsd6 : this is a formula
student : here ill try writing it a different way. the question says: prove this identity
tutorsd6 : please write the steps , so that i can correct , if you doing wrong
student : okay
student : so i changed the RS the cot and tan into cosx/sinx - sinx/cosx
student : which evidently would simplify to cosx-sinx
student : LS: i used the pythagorean identity to change the "1" into sin^2x+cos^2x
student : so the equation would be then (sin^2x+cos^2x - 2sin^2x) / sinxcosx
student : thats where i get stuck
tutorsd6 : then divide each term by sinx cosx
student : done: now im at sinx/cosx + cosx/sinx - 2sin/cos
tutorsd6 : sin^2x / sinxcosx + cos^2x / sinx cosx - 2sin^2x / sinx cosx
tutorsd6 : sinx / cosx + cosx/ sinx - 2sinx / sox
tutorsd6 : tanx + cotx - 2 tanx = cotx - tanx ( proved )
student : oh awesome
student : i dont know how i didnt see that there. the 2 just threw me off i guess
tutorsd6 : it happens ...dont worry
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student : great thanks a lot ! ill let them know a couple kids in my class are stuck ill refer them if they need it
student : again, thanks for your help

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