Question

What is the approximate surface area of the sphere c=37.68?

Answer 1

$A = 4 \pi R x^{2}$
The question does not give you the radius so we have to get it from circumference
Circumference = $\pi$ (diameter)
Divide each side by $\pi$ : Diameter = $\frac{C}{ \pi }$
Radius = 1/2 diameter : $R = \frac{C}{2 \pi }$
Area = $4 \pi R^{2}$
$4 \pi ( \frac{C}{2 \pi })^{2} = 4 \pi \frac{(C) ^{2} }{4 \pi ^{2} }$
Divide top & bottom by $4 \pi$ : A= $\frac{(C) ^{2} }{ \pi }$
Circumference = 37.68 units

$Area = \frac{(37.68)^{2} square units}{ \pi } = 451.93 square units$


451.93 square units