Radius and 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, passing through the center, and is twice the length of the radius.

Front

If the radius of a circle is 7 km, what is the diameter?

Back

The diameter is 14 km (d = 2r).

Front

If the diameter of a circle is 12 m, what is the radius?

Back

The radius is 6 m (r = d/2).

Front

What is the relationship between radius and diameter?

Back

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

Front

What is the circumference of a circle?

Back

The circumference is the distance around the circle, calculated as C = πd or C = 2πr.

Front

True or false: The radius is the longest distance across a circle.

Back

False. The diameter is the longest distance across a circle.

Front

What does the term 'circumference' refer to?

Back

Circumference refers to the total distance around the circle.

Front

If a circle has a radius of 3 m, what is its circumference?

Back

The circumference is approximately 18.85 m (C = 2πr ≈ 2 × 3.14 × 3).

Front

What is the formula to find the radius if you know the diameter?

Back

The formula is r = d/2.