Question

Find the radius and the area of a circle if its circumference is 18 π cm.

Answer 1

Given: Circumference C = 18π cm.

Step-wise calculation:

1. Use C = 2πr.

So, `r = C/(2π)`.

2. `r = (18π)/(2π)` 

= `18/2` 

= 9 cm

3. Area A = πr² 

= π × 9²

= 81π cm²

Radius = 9 cm; Area = 81π cm² (≈ 254.47 cm²).