We will use the cofunction identities and the cosine of a difference formula. Expressing h B in terms of the side and the sine of the angle will lead to the formula of the sine law. Use the formula period 2pB to find the exact value.
Deriving the sine of a triple angle will require the Formulas of sine and cosine of a double angle.
Use addition formulas to derive the identitysinA - B sin A cos B - cos A sin B. So According to The Pythagorean Identities. B c sin. For Equations 1 and 2 let th ½ th From Equation 1 cos 2frac12theta 1 - 2sin2 frac12theta cos theta 1 - 2sin2 frac12theta 2sin2 frac12theta 1 - cos theta.