Which formula is used to find the circumference of a circle when the radius is given?

Question

Responses

C=π2d
upper C equals 2 d

C=πr
upper C equals r

C=πr2
upper C equals r squared

C=π2r

Answer 1

The correct formula to find the circumference of a circle when the radius is given is:

C = 2πr

However, this option is not listed in your responses. Based on the provided options, it seems all the formulas are incorrect or misrepresented. The closest relevant formula from your responses is C = 2d (where \( d \) is the diameter, \( d = 2r \)).

For the radius, the formula for circumference is:

C = 2πr (not listed).