Applying Area and Circumference of Circles

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 does the term 'radius' refer to in a circle?

Back

The radius is the distance from the center of the circle to any point on its circumference.

Front

How do you calculate the area of a circle?

Back

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

Front

What is the relationship between diameter and radius?

Back

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

Front

If the radius of a circle is 9.5 mm, what is the circumference?

Back

C = 2π(9.5) = 19π mm.

Front

What is the circumference of a circle with a diameter of 24 cm?

Back

C = πd = π(24) = 24π cm.

Front

If the circumference of a circle is 36π, what is the radius?

Back

r = C/(2π) = 36π/(2π) = 18 cm.

Front

What is the area of a circle with a radius of 18 cm?

Back

A = π(18)² = 324π cm².

Front

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

Back

Use the formula r = C/(2π).

Front

What is the circumference of a circle with a radius of 14 cm?

Back

C = 2π(14) = 28π cm.