Question

Four alternative answers for the following question is given. Choose the correct alternative.

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

Options

• 9.7

• 1.3

• 2.6

• 4.6

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. ...(P−Q−R)

If the circles touch each other externally, distance between their centres is equal to the sum of their radii.

∴ By theorem of touching circles,

∴ PR = PQ + QR

∴ PR = 5.5 + 4.2

∴ PR = 9.7 cm

∴ The distance between the centres of the circles is 9.7 cm.