Through a given point `P(5, 2)`, secants are drawn to cut the circle `x^2 + y^2 = 25` at point `A_1(B_1),A_2(B_2),A_3(B_3),A_4(B_4) and A_5(B_5)` such that `PA_1 + PB_1 = 5, PA_2 + PB_2 = 6, PA_3 + PB_3 = 7, PA_4 + PB_4 = 8 and PA_5 + PB_5 = 9.` find the value of