Question 206149
SA of a sphere is given by...
- {{{SA = 4 *pi *r^2}}}
Since the radius is half of the diameter (20), r = 10
Next plug the value in
- {{{SA = 4 *pi *r^2}}}
- {{{SA = 4*pi*(10)^2}}}
- {{{SA = 4*pi*100}}}
- {{{SA = 400*pi}}}
= {{{SA = 1256.64ft^2}}}
Then divide SA by 400
and you get 3.14
Assuming that you buy 1 gallon cans of paint it would take 4 cans but it you want the exact number then it would be 3.14 gallons