# Surface areas and volume of spheres and hemispheres

Welcome to class!

In today’s class, we will be talking about surface areas and volume of spheres and hemispheres. Enjoy the class!

### Surface area and Volume Formulas

• ##### Solids:

Solids are three–dimensional objects, bound by one or more surfaces.

• ##### Volume:

The volume of a solid figure is the amount of space enclosed by its bounding surfaces. It is measured in cubic units.

• ##### Surface area:

The surface area of a solid is the total area on the surface of a solid. It is measured in square units.

#### 1. Sphere:

A sphere is a solid figure in the shape of a globe. It is a three-dimensional figure that has all its point the same distance from its centre.

The set of all points in space, which are at a fixed distance from a fixed point, is called a Sphere. The fixed point is the centre of the sphere and the fixed distance is the radius of the sphere.

Therefore,

• The volume of a sphere = 4/3(πr3) cubic units.
• Surface Area (curved and total) of a sphere = 4 πr2 square units.

#### 2. Hemisphere:

A sphere cut by a plane passing through its centre forms two hemispheres. The upper surface of a hemisphere is a circular region.

Therefore,

• The volume of a hemisphere = 2/3(πr3) cubic units.
• Surface Area (curved) of a hemisphere =2πr2 square units.

In our next class, we will be talking about Longitude and Latitude. We hope you enjoyed the class.

Should you have any further question, feel free to ask in the comment section below and trust us to respond as soon as possible.

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