Circumferences and area of circles practice
1. Find the circumference of a circle with a radius of 5 cm.
Circumference = 2 * π * radius
Circumference = 2 * 3.14 * 5
Circumference = 31.4 cm
2. Find the area of a circle with a diameter of 10 cm.
Radius = diameter / 2
Radius = 10 / 2
Radius = 5 cm
Area = π * radius^2
Area = 3.14 * 5^2
Area = 3.14 * 25
Area = 78.5 cm²
3. Find the circumference of a circle with a diameter of 12 inches.
Radius = diameter / 2
Radius = 12 / 2
Radius = 6 inches
Circumference = 2 * π * radius
Circumference = 2 * 3.14 * 6
Circumference = 37.68 inches
4. Find the area of a circle with a circumference of 15 cm.
Radius = Circumference / 2π
Radius = 15 / (2 * 3.14)
Radius = 15 / 6.28
Radius ≈ 2.39 cm
Area = π * radius^2
Area = 3.14 * 2.39^2
Area ≈ 17.96 cm²
5. Find the circumference of a circle with an area of 50 square units.
Radius = √(Area / π)
Radius = √(50 / 3.14)
Radius ≈ √15.92
Radius ≈ 3.99 units
Circumference = 2 * π * radius
Circumference = 2 * 3.14 * 3.99
Circumference ≈ 25.08 units