Area and circumference of circles, arcs, sectors

Front

What is the formula for the circumference of a circle?

Back

C = 2πr, where C is the circumference and r is the radius.

Front

What is the formula for the area of a circle?

Back

A = πr², where A is the area and r is the radius.

Front

If a circle has a radius of 6 meters, what is its circumference?

Back

C = 2π(6) = 12π meters.

Front

If a circle has a radius of 3 meters, what is its area?

Back

A = π(3)² = 9π square meters.

Front

What is a sector of a circle?

Back

A sector is a portion of a circle enclosed by two radii and the arc between them.

Front

What is an arc in a circle?

Back

An arc is a part of the circumference of a circle.

Front

What is the relationship between the radius and diameter of a circle?

Back

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

Front

How do you find the radius if you know the circumference?

Back

Use the formula r = C/(2π).

Front

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

Back

A = π(5)² = 25π cm².

Front

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

Back

C = 2π(4) = 8π cm.