Math worksheet for calculating the area of circles using given radii and diameters.

Let’s solve each problem step by step.

We are finding the area of a circle.
The formula for area of a circle is:
Area = π × r²
where r is the radius (half the diameter).

Sometimes we’re given the diameter, so remember:
→ Radius = Diameter ÷ 2

We’ll use π ≈ 3.14 unless told otherwise.

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Problem 1:
Given: radius = 11
Area = π × 11² = 3.14 × 121 = 379.94

Problem 2:
Given: diameter = 12 → radius = 6
Area = π × 6² = 3.14 × 36 = 113.04

Problem 3:
Given: diameter = 14 → radius = 7
Area = π × 7² = 3.14 × 49 = 153.86

Problem 4:
Given: radius = 1
Area = π × 1² = 3.14 × 1 = 3.14

Problem 5:
Given: diameter = 3 → radius = 1.5
Area = π × (1.5)² = 3.14 × 2.25 = 7.065

Problem 6:
Given: diameter = 23 → radius = 11.5
Area = π × (11.5)² = 3.14 × 132.25 = 415.265

Problem 7:
Given: radius = 10
Area = π × 10² = 3.14 × 100 = 314

Problem 8:
Given: radius = 5
Area = π × 5² = 3.14 × 25 = 78.5

Problem 9:
Given: radius = 9
Area = π × 9² = 3.14 × 81 = 254.34

Problem 10:
Given: diameter = 24 → radius = 12
Area = π × 12² = 3.14 × 144 = 452.16

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Final Answer:
1. 379.94
2. 113.04
3. 153.86
4. 3.14
5. 7.065
6. 415.265
7. 314
8. 78.5
9. 254.34
10. 452.16