Circles and Circumference

Front

What is the formula to calculate the circumference of a circle?

Back

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

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 8, what is the circumference?

Back

Circumference = 2π(8) = 16π.

Front

What is the radius of a circle with a diameter of 20?

Back

Radius = Diameter / 2 = 20 / 2 = 10.

Front

What is π (pi)?

Back

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

Front

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

Back

Radius = Circumference / (2π).

Front

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

Back

Circumference = π(10) = 10π.

Front

If a circle has a circumference of 31.4, what is its diameter?

Back

Diameter = Circumference / π = 31.4 / 3.14 = 10.

Front

What is the relationship between diameter and radius?

Back

The diameter is twice the radius (Diameter = 2 × Radius).

Front

What is the circumference of a circle with a radius of 5?

Back

Circumference = 2π(5) = 10π.