# How do you find the circumference and area of a circle with a diameter of 7cm?

Mar 10, 2018

See a solution process below:

#### Explanation:

The diameter of a circle is twice its radius or: $d = 2 r$

The formula for the circumference of a circle is: $C = 2 \pi r$

Or: $C = 2 r \pi$

Or: $C = \mathrm{dp} i$

Substituting the diameter of the circle from the problem gives:

$C = 7 \text{cm} \cdot \pi$

$C = 7 \pi \text{cm}$

If you approximate $\pi$ with $3.14$ then:

$C \cong 7 \cdot 3.14 \text{cm}$

$C \cong 21.98 \text{cm}$