If two circles of radius 7 cm and 8 cm have two common tangent AB and CD which touch the circle on A, C and B

If two circles of radius 7 cm and 8 cm have two common tangent AB and CD which touch the circle on A, C and B, D respectively and if CD = 26, find the length of AB.

(a)          33

(b)          30

(c)           27

(d)          29

Sol:

Let difference between centers of the circles = a

ATQ,