Question

If two circles touch each other internally then the distance between their centres is equal to

• A. sum of their radii
• B. difference of their radii
• C. product of their radii
• D. smaller of two radii

Answer 1

The correct option is B difference of their radii

Here the center of two circles are $C₁$ and $C₂$ and radius are $r₁$ and $r₂.$ The distance between their centers is the differences of their radii.

When they touch each other internally, the distance between their center

=( big radius - small radius)

$C₁C₂=r₁-r₂$

that means the difference of both radii.

So option B is the correct answer.