Question

1. write the formula for circumference of a circle.

Explanation:

Step1: Recall the relationship between radius and diameter

The diameter \(d\) of a circle is related to the radius \(r\) by \(d = 2r\).

Step2: State the formula in terms of radius

The formula for the circumference \(C\) of a circle in terms of radius \(r\) is \(C=2\pi r\).

Step3: State the formula in terms of diameter

Substituting \(d = 2r\) into \(C = 2\pi r\), we get \(C=\pi d\).

Answer:

The formula for the circumference of a circle is \(C = 2\pi r\) (where \(r\) is the radius) or \(C=\pi d\) (where \(d\) is the diameter).