Circles - Circumference, Radius, Diameter

Front

What is the diameter of a circle?

Back

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

Front

How do you calculate the circumference of a circle?

Back

Circumference = π × diameter (or C = 2 × π × radius).

Front

What is the relationship between radius and diameter?

Back

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

Front

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

Back

10 cm.

Front

If the diameter of a circle is 14 cm, what is the radius?

Back

7 cm.

Front

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

Back

Circumference = 2 × π × radius.

Front

What is π (pi)?

Back

π (pi) is a mathematical constant approximately equal to 3.14, used in calculations involving circles.

Front

What is the circumference of a circle with a diameter of 21 feet?

Back

Approximately 65.94 feet.

Front

What is the radius of a circle with a circumference of 31.4 cm?

Back

5 cm.

Front

What is the area of a circle?

Back

Area = π × radius².