Circles and Arc Length

Front

What is the formula for the circumference of a circle?

Back

C = πd or C = 2πr, where C is circumference, d is diameter, and r is radius.

Front

If the circumference of a circle is 70, what is the length of the semicircle?

Back

35 (Length of semicircle = Circumference / 2).

Front

What is the relationship between diameter and radius?

Back

Diameter is twice the radius (d = 2r).

Front

How do you calculate the diameter if you know the circumference?

Back

Diameter = Circumference / π.

Front

What is the radius of a circle if the circumference is 40?

Back

6.37 (Radius = Circumference / 2π).

Front

If the radius of a circle is 16, what is the circumference?

Back

100.53 (C = 2πr = 2π(16)).

Front

What is the value of π (pi) approximately?

Back

π ≈ 3.14.

Front

How do you find the circumference of a circle with a diameter of 12?

Back

Circumference = πd = π(12) ≈ 37.69.

Front

What is the diameter of a circle if the circumference is 28.27?

Back

9 (Diameter = Circumference / π).

Front

What is the formula for the area of a circle?

Back

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