*Sin & cos as projections
Actually cos & sin gives us an ideas of projections (shadows) of a line on x & y axis respectively. Consider a line of length L making an anticlockwise angle q with + x axis. Let Lx (= ON) &Ly (= OM) be its x & y projections, then
If θ is increased from 00 to 900, then cosθ decreases & sinθ increases.
sin2 θ + cos2 θ = 1
cosec2 θ – cot2 θ = 1
For integral values of n