LET’S TRY ONE
A circle has radius 2 cm. What is its exact area in square centimeters, written as a multiple of π?
4π
Area = πr2 = π × 22 = 4π square centimeters.
Learning steps & teaching tips
Use radius squared to express an exact circle area in terms of π.
- Square the radius and keep π as a symbol until an approximation is requested.
- Work through the example and explain why each operation is used.
- Estimate or use another method to check the result before choosing.
Try it together
Work with a partner: solve one example, explain the method, then change one number and predict what changes.
Square the radius and keep π as a symbol until an approximation is requested.