In any triangle, when the bisector of a given angle intercept the opposite side in S, we have the following proportionality: (am taking your triangle)
QP/QR = SP/SR
To be able to calculate the perimeter we need to know SP, which can be extracted from the formula QP/QR = SP/SR
QP/QR = SP/SR → 36/15 =SP/11 ; SP = (11x36)/15 = 26.4
And the perimeter is : 36+15+ (11+26.4) = 77.4 units
