# How do you prove  -2cos^2x tan(-x)=sin2x?

##### 1 Answer
Nov 28, 2015

its a very easy ques as the math here in india is very tough.we can write tan(-x) = -tanx
therefore equation becomes cos^2x.tanx
we can write tanx = sinx/cosx
then the equation becomes 2sinx cosx which is equal to sin2x