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A circle’s diameter is ${6\ {\rm m}}\text{.}$

For the answers below, type pi for $\pi\text{,}$ m for meters, and m^2 for square meters.

This circle’s circumference, in terms of $\pi\text{,}$ is
.

This circle’s circumference, rounded to the hundredth place, is
.

This circle’s area, in terms of $\pi$ is
.

This circle’s area, rounded to the hundredth place, is
.

Solution

We use $r$ to represent radius and $d$ to represent diameter. In this problem, it’s given that the diameter is ${6\ {\rm m}}\text{.}$ A circle’s radius is half as long as its diameter, so the radius is ${3\ {\rm m}}\text{.}$

Throughout these computations, all quantities have units attached, but we only show them in the final step.

$\begin{aligned}[t] c\amp = \pi d\\ \amp = \pi \cdot 6\\ \amp = {6\pi\ {\rm m}} \end{aligned}$

$\begin{aligned}[t] c\amp = \pi d\\ \amp \approx 3.1415926 \cdot 6\\ \amp \approx {18.85\ {\rm m}} \end{aligned}$

$\begin{aligned}[t] A\amp = \pi r^2\\ \amp = \pi \cdot 3^2\\ \amp = \pi \cdot 9\\ \amp = {9\pi\ {\rm m^{2}}} \end{aligned}$

$\begin{aligned}[t] A\amp = \pi r^2\\ \amp \approx 3.1415926 \cdot 3^2\\ \amp \approx 3.1415926 \cdot 9\\ \amp \approx {28.27\ {\rm m^{2}}} \end{aligned}$