Trigonometrysinsin θ = cos ( θ - ½ π )coscos θ = sin ( θ + ½ π )Small Angle ApproximationsWhen θ is extremely small, for example if one cathetus is several orders of magnitude than the other, we can use the following approximations:sin θ ≈ θcos θ ≈ 1 - ½ θ2tan θ ≈ θ