Area and Circumference of Circles

Front

What is the formula for the area of a circle?

Back

A = πr²

Front

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

Back

20ft

Front

What is the formula for the circumference of a circle using the radius?

Back

C = 2πr

Front

If the diameter of a circle is 19 inches, what is the radius?

Back

9.5 inches

Front

What is the circumference of a circle with a diameter of 3 centimeters?

Back

9.42 cm

Front

What does π (pi) represent in circle calculations?

Back

π is a constant approximately equal to 3.14, representing the ratio of the circumference to the diameter of a circle.

Front

How do you calculate the diameter if you know the radius?

Back

Diameter = 2 * Radius

Front

What is the relationship between diameter and circumference?

Back

Circumference = π * Diameter

Front

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

Back

A = π(5)² = 25π cm²

Front

What is the approximate value of the circumference of a circle with a radius of 7cm?

Back

C = 2π(7) ≈ 43.98 cm