# If the radius of a circle is 9 cm what is the area and circumference?

Oct 11, 2015

Area: $81 \setminus \pi$
Circumference: $18 \pi$
Area = ${r}^{2} \cdot \setminus \pi = {9}^{2} \cdot \setminus \pi = 81 \cdot \setminus \pi$
Circumference = $2 \cdot r \cdot \setminus \pi = 2 \cdot 9 \cdot \pi = 18 \cdot \setminus \pi$