Finding the Radius and Diameter of Circles

Front

What is the diameter of a circle?

Back

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

Front

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

Back

Multiply the radius by 2. (Diameter = 2 × Radius)

Front

What is the radius of a circle?

Back

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

Front

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

Back

Divide the diameter by 2. (Radius = Diameter ÷ 2)

Front

What is the circumference of a circle?

Back

The circumference is the distance around the circle.

Front

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

Back

Circumference = π × Diameter or 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

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

Back

The diameter is 10 cm.

Front

If the diameter of a circle is 20 m, what is the radius?

Back

The radius is 10 m.

Front

What is the relationship between radius and diameter?

Back

The diameter is always twice the length of the radius.