As we know,

Tangents drawn from an external point are equal, We have

AF = AE = 4 cm

[Tangents from common point A]

BF = BD = 3 cm

[Tangents from common point B]

CE = CD = x (say)

[Tangents from common point C]

Now,

AC = AE + CE

11 = 4 + x

x = 7 cm [1]

and, BC = BD + BC

BC = 3 + x = 3 + 7 = 10 cm