Question

Robert drew a circle and labeled the circle s. He used the expression 12pi to find the circumference of the circle in meters. Which is the following could be the circle Robert drew?

Answer 1

This question is about lenght of the circumference.

If we have a circumference with radius R, then its lenght s is given by:

$S\text{ = 2 }\cdot\text{ }\pi\text{ }\cdot\text{ R}$

If Robert says he can use 36 m to draw the circumference, then S = 36 m.

Let's plug that information on the equation above.

$36=2\cdot\pi\cdot R$

We know that:

$\pi=3$

So, we get:

$36=2\cdot3\cdot R$

Solving for R:

$36=6\cdot R$

$R=\frac{36}{6}$$R=6\text{ m}$

Looking up we can see the correct answer is option B.