Two circles of radii 5 cm and 2-8 cm touch each other. Find the distance between their centers if they touch : (i) externally (ii) internally.

Solution:

Radii of the circles are 5 cm and 2.8 cm.

i.e. OP = 5 cm and CP = 2.8 cm.

(i) When the circles touch externally,

then the distance between their centers = OC = 5 + 2.8

= 7.8 cm.

(ii) When the circles touch internally,

then the distance between their centers = OC = 5.0 – 2.8

= 2.2 cm