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

Difference of their radius

Sum of their radius

Product of their radius

None of these

If two circles touch internally, the distance between their centers is the difference of their radii: r₁ - r₂.

r₁ is the radius of the larger circle, and r₂ is the radius of the smaller circle.

If the sum of the radii equals the distance between the centers, the circles touch externally.