Area and Circumference of Circles

Front

What is the definition of a radius?

Back

A radius is a line segment from the center of a circle to any point on its circumference.

Front

What is the definition of a diameter?

Back

A diameter is a line segment that passes through the center of a circle and has its endpoints on the circle.

Front

How do you calculate the circumference of a circle?

Back

Circumference = 2 × π × radius.

Front

What is the value of π (Pi) commonly approximated as?

Back

π is commonly approximated as 3.14.

Front

What is the formula for the area of a circle?

Back

Area = π × radius².

Front

If the radius of a circle is 7 cm, what is its circumference?

Back

Circumference = 2 × 3.14 × 7 = 43.96 cm.

Front

If the radius of a circle is 10 m, what is its area?

Back

Area = 3.14 × 10² = 314 m².

Front

What is the relationship between radius and diameter?

Back

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

Front

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

Back

Radius = Circumference / (2 × π) = 31.4 / (2 × 3.14) = 5 m.

Front

What is the circumference of a circle with a radius of 13.8 m?

Back

Circumference = 2 × 3.14 × 13.8 = 86.70 m.