Area of a Circle

Front

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

Back

Area = π × r², where r is the radius of the circle.

Front

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

Back

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

Front

What is the area of a circle with a radius of 9 cm?

Back

Area = π × (9 cm)² ≈ 254 cm².

Front

What does the term 'radius' refer to in a circle?

Back

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

Front

If a circle has a diameter of 10 cm, what is its area?

Back

Area = π × (5 cm)² ≈ 78.5 cm².

Front

What is the relationship between diameter and radius?

Back

Diameter = 2 × Radius.

Front

How do you convert diameter to radius?

Back

Divide the diameter by 2.

Front

What is the area of a circle with a diameter of 30 feet?

Back

Area = π × (15 ft)² ≈ 706.5 ft².

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.