CIRCLES REVIEW: Equations, Angles, Sectors

Front

What is the formula for the area of a circle?

Back

Area = πr², where r is the radius.

Front

How do you find the circumference of a circle?

Back

Circumference = 2πr or Circumference = πd, where d is the diameter.

Front

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

Back

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

Front

What is the equation of a circle with center (h, k) and radius r?

Back

(x - h)² + (y - k)² = r².

Front

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

Back

Area = π(4)² = 16π ≈ 50.24 square units.

Front

What is the measure of a full circle in degrees?

Back

360 degrees.

Front

How do you calculate the area of a sector of a circle?

Back

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

Front

What is the measure of a semicircle in degrees?

Back

180 degrees.

Front

If the radius of a circle is 5, what is the circumference?

Back

Circumference = 2π(5) = 10π ≈ 31.42 units.

Front

What is the formula to find the length of an arc?

Back

Length of arc = (θ/360) × 2πr, where θ is the angle in degrees.