This is the basic and conceptual question from Chapter name- circles

Topic – Angle properties of circles

Chapter number- 15

We have two circles of radii 5 cm and 2-8 cm touch each other and we have to find the distance between their centres if they touch : (i) externally (ii) internally.

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Understanding ICSE Mathematics

Question 5, exercise 15.3

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 centres = OC = 5 + 2.8 = 7.8 cm.

(ii) When the circles touch internally,

then the distance between their centres = OC = 5.0 – 2.8 = 2.2 cm