Question

The formula for the circumference of the circle, $C$ is $2\pi$r.

Make 'r' as subject of the formula.

• A. $C=2\pi r$
• B. $2=Cr$
• C. $r=\frac{C}{2\pi }$
• D. $r=2C$

Answer 1

The correct option is C $r=\frac{C}{2\pi }$

Subject of a formula is the variable which is expressed in terms of the other variables involved in the formula.
So, $r=\frac{C}{2\pi }$
where $r$ is the subject of the formula.

So, option C is correct.