Two circles are drawn about the same centre. The ring between them has area 264 cm² and the outer radius is 10 cm. Find the inner radius in cm. Take π = 22/7.

Question

Accepted Answer

4. π(R² − r²) = 264 gives (22/7)(100 − r²) = 264, so 100 − r² = 264 × 7/22 = 84, r² = 16 and r = 4 cm. (6 cm is the width of the ring, 10 − 4, which is what students answer when they stop one step early.)

Two circles are drawn about the same centre. The ring between them has area $264 cm^{2}$ and the outer radius is 10 cm. Find the inner radius in cm. Take π = 22/7.

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More Areas & Volumes practice

Two circles are drawn about the same centre. The ring between them has area 264cm2 and the outer radius is 10 cm. Find the inner radius in cm. Take π = 22/7.

Step-by-Step Solution

Master this topic in 30 minutes a day.

More Areas & Volumes practice

Two circles are drawn about the same centre. The ring between them has area $264 cm^{2}$ and the outer radius is 10 cm. Find the inner radius in cm. Take π = 22/7.