(Sin A/(1 Cos A)) ((1 Cos A)/Sin A)= 2Csc A


1-Tan^2(-A)=Sec^2 A


(1-tan^2 A)/(1 Tan^2 A)=2Cos^2 A -1

1. Start by combining the fractions.

2. Use the fact that tan(-a) = -tan(a)

3. Convert everything to the cos and sin ratios and simplify the fraction on the left.

Can you try those out for a start?