Geo 11.3 Area of Circles and Sectors

Front

What is the formula for the area of a circle?

Back

A = πr², where A is the area and r is the radius.

Front

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

Back

Use the formula r = √(A/π), where A is the area.

Front

What is the relationship between diameter and radius?

Back

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

Front

If the diameter of a circle is 10 cm, what is the radius?

Back

5 cm.

Front

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

Back

A = π(7)² ≈ 153.94 m².

Front

How do you convert area from square inches to square feet?

Back

Divide the area in square inches by 144 (since 1 square foot = 144 square inches).

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 find the area of a sector?

Back

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

Front

If a circle has an area of 50π cm², what is the radius?

Back

r = √(50) cm ≈ 7.07 cm.

Front

What is the area of a circle with a diameter of 12 inches?

Back

A = π(6)² = 36π in² ≈ 113.1 in².