How do I proof this equation is an identity? 1-sec(x)cos³(x)=sin²(x)
#1 - (1/cosx)cos^3x= sin^2x#
#1 - cos^2x = sin^2x#
#LHS = RHS#
Hopefully this helps!
And reciprocal identity:
Use these three identities (the third one is pretty much the same as the second, but switched around a little):
To complete the proof, I'll start with the left-hand side of the equation and manipulate it until it equals the right-hand side of the equation:
That is the proof. Hope this helped!