Question

Two similar circles are shown. The circumference of the larger circle, with radius OB, is 3 times the circumference of the smaller circle, with radius OA.

Two circles are shown. The smaller circle has radius O A and the larger circle has radius O B.

Radius OB measures x units. Which expression represents the circumference of the smaller circle with radius OA?

(StartFraction pi Over 3 EndFraction)x units
(StartFraction 2 pi Over 3 EndFraction)x units
2πx units
6πx units

Answer 1

Circumference scales with radius, and the larger circumference is 3 times the smaller, so the smaller circumference is (1/3) of the larger: (1/3)(2πx) = (2π/3)x.