Area and Circumference of a Circle

Front

What is the formula for the area of a circle?

Back

The area of a circle is given by the formula: A = πr², where A is the area and r is the radius.

Front

What is the formula for the circumference of a circle?

Back

The circumference of a circle is given by the formula: C = 2πr, where C is the circumference and r is the radius.

Front

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

Back

A = π(10)² = 100π ≈ 314.16 cm².

Front

If the radius of a circle is 7 cm, what is its circumference?

Back

C = 2π(7) = 14π ≈ 43.98 cm.

Front

What is the value of π (pi) approximately?

Back

π (pi) is approximately 3.14.

Front

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

Back

To find the radius from the circumference, use the formula: r = C/(2π).

Front

What is the area of a circle with a radius of 5 m?

Back

A = π(5)² = 25π ≈ 78.54 m².

Front

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

Back

C = πd = π(12) ≈ 37.68 cm.

Front

If a circle has an area of 50 cm², what is the radius?

Back

r = √(A/π) = √(50/π) ≈ 3.99 cm.

Front

What is the relationship between diameter and radius?

Back

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