Sorry but i dont know how to use latex yet or to add mathematical symbols somehow. 1. The problem statement, all variables and given/known data Prove that 1-sin2θ/cos2θ = 1-tanθ/1+tanθ 2. Relevant equations sin2θ = 2tanθ/1+tan2θ and cos2θ =1-tan2θ/1+tan2θ I have allready proved from a previous exercise those two above so i pressume they may be useful. 3. The attempt at a solution 1-sin2θ/cos2θ = 1-2tanθ/1+tan2θ/1-tan2θ/1+tan2θ= i then multiply the fraction with (1+tan2θ) and i am left with 1-2tanθ/1-tan2θ i have tried various things but i suppose this is the way to go.. maybe not, i dont know, i am stuck. Can someone help me on that one please?