Circumference and Area of Circles Review

Front

What is the formula for calculating the area of a circle?

Back

A = π·r², where A is the area and r is the radius.

Front

How do you calculate the circumference of a circle using the diameter?

Back

C = π·d, where C is the circumference and d is the diameter.

Front

What is the relationship between radius and diameter?

Back

The diameter is twice the length of the radius (d = 2·r).

Front

If a circle has a radius of 5 feet, what is its area?

Back

A = π·(5)² = 25π ≈ 78.54 ft².

Front

What is the circumference of a circle with a radius of 3 feet?

Back

C = 2·π·3 = 6π ≈ 18.85 feet.

Front

What is the diameter of a circle with a radius of 10 inches?

Back

d = 2·r = 2·10 = 20 inches.

Front

How do you convert the radius to diameter?

Back

Multiply the radius by 2.

Front

What is the area of a circle with a diameter of 12 feet?

Back

A = π·(6)² = 36π ≈ 113.10 ft².

Front

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

Back

C = π·8 ≈ 25.13 inches.

Front

If the area of a circle is 50π square units, what is the radius?

Back

r = √(50) ≈ 7.07 units.