Question

Surface Area of a sphere, A grapefruit with C = 14cm.

Answer 1

Surface area SA: $4\pi r^2$
Circumference C: $2\pi r$ dividing this you get $7=\pi r$ and $r= \frac{7}{\pi}$

Now let's input the radius $r$ into the Surface area formula...
$4\pi r^2\rightarrow 4\pi(\frac{7}{\pi})^2=4\pi(\frac{49}{\pi^2})=\frac{196}{\pi}$