Area and Circumference of Circles

Front

What is the formula for the area of a circle?

Back

Area = π × r², where r is the radius.

Front

What is the formula for the circumference of a circle?

Back

Circumference = 2 × π × r or Circumference = π × d, where d is the diameter.

Front

If the diameter of a circle is 10 meters, what is the radius?

Back

5 meters.

Front

What is the relationship between diameter and radius?

Back

Diameter = 2 × Radius.

Front

What is the area of a circle with a radius of 7 meters?

Back

Area = π × 7² ≈ 153.94 m².

Front

What is the circumference of a circle with a radius of 4 meters?

Back

Circumference = 2 × π × 4 ≈ 25.13 m.

Front

If the radius of a circle is doubled, how does the area change?

Back

The area increases by a factor of 4.

Front

What is the diameter of a circle with a radius of 12 inches?

Back

24 inches.

Front

What is the area of a circle with a diameter of 8 cm?

Back

Area = π × (4)² ≈ 50.27 cm².

Front

What is the circumference of a circle with a diameter of 10 feet?

Back

Circumference = π × 10 ≈ 31.42 feet.