Circle - Area and Circumference

Front

What is the formula for the circumference of a circle?

Back

C = 2πr, where r is the radius.

Front

What is the formula for the area of a circle?

Back

A = πr², where r is the radius.

Front

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

Back

5 cm (Radius is half of the diameter).

Front

What is the relationship between radius and diameter?

Back

Diameter = 2 × Radius.

Front

What is the circumference of a circle with a radius of 7 inches?

Back

C = 2π(7) ≈ 43.98 inches.

Front

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

Back

A = π(4)² ≈ 50.27 square meters.

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 6 inches?

Back

12 inches (Diameter = 2 × Radius).

Front

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

Back

C = π(8) ≈ 25.13 cm.

Front

If the area of a circle is 78.5 square units, what is the radius?

Back

r ≈ 5 units (A = πr², solve for r).