Area and Circumference of Circles

Front

What is the formula for the circumference of a circle?

Back

The circumference (C) of a circle is calculated using the formula: C = 2πr, where r is the radius.

Front

What is the formula for the area of a circle?

Back

The area (A) of a circle is calculated using the formula: A = πr², where r is the radius.

Front

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

Back

The diameter (d) of a circle is twice the radius: d = 2r.

Front

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

Back

The diameter is 20 cm.

Front

If the diameter of a circle is 30 cm, what is the radius?

Back

The radius is 15 cm.

Front

What is the value of π (pi) approximately?

Back

π is approximately 3.14.

Front

Calculate the circumference of a circle with a radius of 7 cm.

Back

C = 2π(7) = 14π ≈ 43.98 cm.

Front

Calculate the area of a circle with a radius of 5 cm.

Back

A = π(5)² = 25π ≈ 78.54 cm².

Front

What is the circumference of a circle with a diameter of 12 inches?

Back

C = π(12) ≈ 37.68 inches.

Front

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

Back

A = π(5)² = 25π ≈ 78.54 m².