Explanation: The tangent half-angle formula is shown in the attached image We have: alpha = 7pi / 8 alpha/2 = 7pi / 16
Substitute in the formula with the alpha and alpha/2 as follows: tan (7pi/8) = [2tan(7pi / 16)] / [1 - tan(7pi / 16)tan(7pi / 16)] tan (7pi/8) = -4.4142
