Circumference and Area of a Circle

Front

What is the formula for the circumference of a circle?

Back

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

Front

What is the formula for the area of a circle?

Back

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

Front

What does 'π' (pi) represent in mathematics?

Back

π (pi) is a constant approximately equal to 3.14, representing the ratio of the circumference of a circle to its diameter.

Front

If the radius of a circle is 5 cm, what is its circumference?

Back

C = 2π(5) = 31.4 cm.

Front

If the diameter of a circle is 10 m, what is its area?

Back

A = π(5)² = 78.5 m².

Front

What is the relationship between diameter and radius?

Back

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

Front

How do you convert circumference to diameter?

Back

Use the formula d = C/π.

Front

What is the circumference of a circle with a radius of 7 inches?

Back

C = 2π(7) ≈ 43.96 inches.

Front

What is the area of a circle with a radius of 3 feet?

Back

A = π(3)² ≈ 28.27 square feet.

Front

If a circle has a circumference of 62.8 cm, what is its radius?

Back

r = C/(2π) = 62.8/(2π) ≈ 10 cm.