Surface area of a sphere 4pr² r is the length of the spheres radius To find the surface area of a sphere multiply the radius r by itself r x r or r². The total area of the surface of a three-dimensional object. Calculate the surface area by working out the area of each face and adding them together.
L is the length.
The next step is to calculate the surface area of 3-D figures. E lateral edge length. R is the radius. The total surface area of hemisphere is equal to sum of half of surface area of sphere and area of its circular base.