Question

Find the area and the circumference of a circle with diameter 7cm .

Answer 1

if the diameter is 7 units, the radius is half that, or 3.5


`\bf \textit{area of a circle}\\\\ A=\pi r^2\qquad \boxed{r=3.5}\qquad A=3.5^2\pi \implies A=12.25\pi \\\\\\ \textit{circumference of a circle}\\\\ C=2\pi r\qquad \boxed{r=3.5}\qquad C=2\pi 3.5\implies C=7\pi`