Grade 10 · Math
Find a circle’s exact area practice
Use radius squared to express an exact circle area in terms of π.
Opening your practice adventure…
Try a sample
A circle has radius 9 cm. What is its exact area in square centimeters, written as a multiple of π?
- 81π
- 324π
- 18π
- 83π
See the answer & why
81π
Area = πr2 = π × 92 = 81π square centimeters.
A little hint: Use the radius, not the diameter, in πr2.
A teaching tip
Square the radius and keep π as a symbol until an approximation is requested.