Question 997682
Prove 2cot2xcosx=cscx-2sinx
Rewrite like this:
(cos(2x)/sin(2x))2cos(x)=? 1/sinx-2sin(x)
(2cos(x)cos(2x)/sin(2x))=? 1-2sin(x)^2/sin(x)
cross multiply and you get:
2cos(x)1-2sin(x)^2sin(x)=? sin(2x)(1-2sin(x)^2)
2cos(x)sin(x)-4cos(x)sin(x)^3=? sin(2x)(1-2sin(x)^2)
2cos(x)sin(x)-4cos(x)sin(x)^3=? 2cos(x)sin(x)-4cos(x)sin(x)^3
True, identity verified
NOTE: the question mark goes over the equal sign until the identity is proven true or false.