A sphere is a ballshaped object. A hemisphere is half of a sphere.
There is one key measurement for a sphere, that is the radius, r.
Volume and Surface Area of a Sphere
The volume and surface area of a sphere are found using two formulae.
Volume V = ^{4}⁄_{3} π r^{3}
Surface Area S = 4 π r^{2}

Examples of Sphere Calculations
Examples

Calculation

Find the volume of the sphere below. Use π = 3.1 
The radius of the sphere is 5 cm. V = ^{4}⁄_{3} π r^{3} V = ^{4}⁄_{3} × 3.1 × 5^{3} V = 516.7 cm^{3} (to 4 sig. fig.)

For the sphere shown above, find the surface area. Use π = 3.1 
Surface area = 4π r^{2} Surface area = 4 × 3.1 × 5^{2} Surface area = 310 cm^{2} 
A sphere has a volume of 900 cm^{3}, what is its radius? 