Lets begin by writing the double-angle formula for sine. For example to find sin 165o follow these steps. Given find a sin 2th b Solution.
If we now replace A by 12 A and take the square root we get.
Cos 2 A cos 2 A sin 2 A cos 2 A 1 cos 2A 2cos 2 A 1. Write the double-angle formula for. The double-angle formulas can be quite useful when we need to simplify complicated trigonometric expressions later. The half angle formula for Tangent is helpful when you need to determine the exa.