Area and Circumference

Front

What is the formula for the circumference of a circle?

Back

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

Front

How do you calculate the diameter of a circle if you know the circumference?

Back

Diameter can be calculated using the formula d = C/π.

Front

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

Back

The diameter is twice the radius: d = 2r.

Front

What is the formula for the area of a circle?

Back

A = πr², where r is the radius.

Front

How do you find the radius of a circle if you know the area?

Back

Radius can be calculated using the formula r = √(A/π).

Front

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

Back

C = πd = π(10) ≈ 31.42 cm.

Front

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

Back

A = π(5)² = 25π ≈ 78.54 square inches.

Front

What does the term 'circumference' refer to?

Back

Circumference is the distance around the circle.

Front

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

Back

A = π(7)² = 49π ≈ 153.94 square cm.

Front

How can you express the circumference of a circle in terms of its radius?

Back

C = 2πr.