The radii of two circles are 10 cm and 4 cm. The length of a common external tangent is 8 cm. What is the distance between their centers?
Show answer & explanation
Correct answer: B
Explanation
Given:
r₁ = 10 cm
r₂ = 4 cm
Common external tangent = 8 cm
Formula:
External tangent² = d² − (r₁ − r₂)²
8² = d² − (10 − 4)²
64 = d² − 36
d² = 100
d = 10 cm