Area and Circumference of Circles

Front

What is the area of a circle?

Back

The area of a circle is the space contained within its circumference, calculated using the formula A = πr², where r is the radius.

Front

What is the circumference of a circle?

Back

The circumference of a circle is the distance around it, calculated using the formula C = 2πr or C = πd, where d is the diameter.

Front

What is the radius of a circle?

Back

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

Front

What is the diameter of a circle?

Back

The diameter is the distance across the circle through its center, equal to twice the radius.

Front

If the radius of a circle is 5, what is the area?

Back

A = π(5)² = 25π, approximately 78.54.

Front

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

Back

The radius is half of the diameter, so the radius is 5.

Front

What is the formula for the circumference of a circle given the radius?

Back

C = 2πr.

Front

What is the formula for the area of a circle given the diameter?

Back

A = π(d/2)² = (π/4)d².

Front

If a circle has a circumference of 31.4, what is the radius?

Back

C = 2πr, so r = C/(2π) = 31.4/(2π) ≈ 5.

Front

What is π (pi)?

Back

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