Question

Two circles having radii 3.5 cm and 4.8 cm touch each other internally. Find the distance between their centres.

Answer 1

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

Here, QR = 3.5 cm, PR = 4.8 cm

The two circles touch each other internally.

By theorem of touching circles,

P – Q – R

PQ = PR – QR   ...[The distance between the centres of circles touching internally is equal to the difference in their radii.]

= 4.8 – 3.5

= 1.3 cm

∴ The distance between the centres of the circles is 1.3 cm.