Geo 11.3 Area of Circles and Sectors

Front

What is the formula for the area of a circle?

Back

Area = πr², where r is the radius of the circle.

Front

How do you find the radius of a circle if you know the area?

Back

Use the formula r = √(Area/π).

Front

What is the area of a circle with a radius of 5 m?

Back

Area = π(5)² = 25π ≈ 78.54 m².

Front

If a circle has an area of 113.1 m², what is its radius?

Back

Radius = √(113.1/π) ≈ 6 m.

Front

What is a sector of a circle?

Back

A sector is a portion of a circle enclosed by two radii and the arc between them.

Front

How do you calculate the area of a sector?

Back

Area of sector = (θ/360) × πr², where θ is the angle in degrees.

Front

What is the area of a sector with a radius of 10 cm and an angle of 90 degrees?

Back

Area = (90/360) × π(10)² = 25π ≈ 78.54 cm².

Front

What is the relationship between the diameter and radius of a circle?

Back

Diameter = 2 × Radius.

Front

If the diameter of a circle is 14 cm, what is its area?

Back

Radius = 7 cm; Area = π(7)² = 49π ≈ 153.94 cm².

Front

What is the area of a circle with a radius of 7 cm?

Back

Area = π(7)² = 49π ≈ 153.94 cm².