Centre of circle x2 + y2 = 16 is origin and radius is 4 line y = x passes through origin and cuts the circle at A.
Then solving x2 + y2 = 16 and y = x
x = 2√2
∴ Coordinate of A(2√2, 2√2), P(4, 0) and B(2√2, 0)
Thus, rquired area = Area AOBA + Area ABPA