If d1,d2,d3 are the diameters of the three escribed circles of a triangle, then d1d2 + d2d3 + d3d1 is equal to
(a) Δ2
(b) 4s2
(c) 2Δ2
(d)4Δ2
Correct option (b) 4s2
r1r2 + r2r3 = 4s2
4r1r2 + 4r2r3 + 4r3r1 = 4s2⇒ 4d1d2 + 4d2d3 + 4d3d1 = 4s2