Question

Two circles of radii 5.5 cm and 4.2 cm touch each other externally. Find the distance between their centres.

Answer 1

Let the two circles having centres P and R touch each other externally at point Q. 

Here, PQ = 5.5 cm, QR = 4.2 cm

The two circles touch each other externally. 

∴ By theorem of touching circles, 

P – Q – R 

PR = PQ + QR

= 5.5 + 4.2 

= 9.7 cm 

[The distance between the centres of the circles touching externally is equal to the sum of their radii]