Need help with this please: 1. The problem statement, all variables and given/known data (1 + cosθ + isinθ) / (1 - cosθ - isinθ) = icotθ/2 The first step in the solutions shows: (2cos^2θ/2 + i2sinθ/2cosθ/2) / (2sin^2θ/2 - i2sinθ/2cosθ/2) 2. Relevant equations I can't get there. 3. The attempt at a solution I tried multiplying by: (1 - cosθ + isinθ) / (1 - cosθ + isinθ), with no luck. the top line of my attempt shows i2sinθ + i2sinθcosθ because 1-cos^2θ=sin^2θ my signs could be wrong but still. how does the θ become θ/2. this is doing my head in. maybe just sleep on it.