9.1-9.4

Front

What is the formula for the circumference of a circle?

Back

C = πd, where d is the diameter.

Front

How do you calculate the diameter of a circle if you know the radius?

Back

Diameter (d) = 2 × Radius (r).

Front

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

Back

The diameter is twice the length of the radius.

Front

How do you find the arc length of a circle?

Back

Arc Length = (θ/360) × C, where θ is the angle in degrees and C is the circumference.

Front

What is the formula for the area of a circle?

Back

A = πr², where r is the radius.

Front

If a circle has a radius of 10 feet, what is its circumference?

Back

C = 2π(10) = 20π feet.

Front

What is the measure of a full circle in degrees?

Back

360 degrees.

Front

How do you convert radians to degrees?

Back

Degrees = Radians × (180/π).

Front

What is the measure of a semicircle in degrees?

Back

180 degrees.

Front

If the arc length of a circle is 5π, what is the angle in degrees?

Back

θ = (Arc Length / Circumference) × 360 = (5π / 2πr) × 360.