(Csc x)(sec x)=2csc2x

Question

I have to prove the identity. But need help

Answer 1

sarah, this identity requires similar work to the other one that you submitted & I just answered.

 

replace csc x by reciprocal of sin x; replace sec x by reciprocal of cos x.

Then left hand side becomes RECIPROCAL of sinx cosx, i.e. reciprocal of ½sin2x and that's equivalent to the right hand side, as I hope you will see.