Area of Circles

Front

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

Back

Area = π × r², where r is the radius.

Front

If the diameter of a circle is 18 cm, what is the radius?

Back

Radius = Diameter / 2 = 18 cm / 2 = 9 cm.

Front

Calculate the area of a circle with a radius of 9 cm. (Round to the nearest hundredth)

Back

Area = π × (9 cm)² = 254.47 cm².

Front

What is the distance from the center of a circle to any point on the circle called?

Back

Radius.

Front

What is the distance across a circle through its center called?

Back

Diameter.

Front

If a circle has a radius of 4 cm, what is its area?

Back

Area = π × (4 cm)² = 50.24 cm².

Front

What is π (pi) approximately equal to?

Back

π ≈ 3.14.

Front

If the radius of a circle is doubled, how does the area change?

Back

The area increases by a factor of four.

Front

What is the area of a circle with a radius of 10 cm? (Round to the nearest hundredth)

Back

Area = π × (10 cm)² = 314.16 cm².

Front

What is the relationship between diameter and radius?

Back

Diameter = 2 × Radius.