Two circles of radius 13 cm and 15 cm intersect each other at points A and B. If the length of the common chord is 24 cm, then what is the distance between their centres?

Answer: Option D

In ΔADO
OD = $$\sqrt{{\left(15\right)}^2-{\left(12\right)}^2}$$    = 9 cm
In ΔADC
DC = $$\sqrt{{\left(13\right)}^2-{\left(12\right)}^2}$$    = 5 cm
or use Triplet
5, 12, 13 and 9, 12, 15
∴ OC = DC + OD = 5 + 9 = 14 cm