Circumference and Area of Circles

Front

What is the formula for the circumference of a circle?

Back

C = 2πr or C = πd, where r is the radius and d is the diameter.

Front

What is the circumference of a circle with a radius of 12.5 mm?

Back

78.5 mm

Front

What is the circumference of a circle with a diameter of 56 m?

Back

175.8 m

Front

What is the definition of circumference?

Back

The measurement around the circle.

Front

If a circular swimming pool has a diameter of 21 feet, what is its circumference?

Back

65.94 ft

Front

What is the relationship between diameter and radius?

Back

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

Front

What is the value of π (pi) approximately?

Back

3.14 or 22/7.

Front

How do you find the area of a circle?

Back

A = πr², where r is the radius.

Front

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

Back

A = π(7)² = 154 cm² (approximately).

Front

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

Back

20 cm.