A sphere is a regular three-dimensional object in which every cross-section is a circle.

**Formula to calculate surface area of a sphere**.

Where:

r – is the radius of the circle.

π – is a constant estimated to be 3.142.

**Example:**

A globe has a radius of 20 cm .Calculate the surface area of the globe.

In this case a globe is a good example of a sphere.So we are going to use the formula used to find the surface area of the sphere to calculate the surface area of the globe.

Therefore, the surface area of the globe is 5027.2 cm² .