# Question #87314

##### 1 Answer

Oct 29, 2017

If we assume it is very thin, then it’s not too hard.

#### Explanation:

The surface area will just be double the external area which we find from half the area of a sphere.

That means it is just the area of a sphere which is given by

If you are given a thickness, then you would need to work out the area of each half with the different value of the radius, then add the area of the circular (cut) surface from the difference in areas of the inner and outer circle.