User:Tarun seeker/Introduction to calculus

Here are my answers, writing them caused a lot of problems so it took a bit time Ans 1. tan θ = ±(sin θ/square root(1-sin^2 θ)) Ans 2. sec θ Ans 3. sin^2 θ + cos^2 θ = (sin^2 θ + cos^2 θ)/cos^2 θ = tan^2 θ + 1 = sec^2 θ Ans 4i. cos 2θ = cos^2 θ - sin^2 θ Ans 4ii. cos (θ/2) = square root( (cosθ + 1)/2) Ans 4iii. cos^2 θ = (cos 2θ + 1)/2 Ans 4iv. cos^3 θ = (cos 3θ + 3 cos θ)/4 Thanks, Tarun