# Volume of a Prism - Formula, Derivation, Definition, Examples

A prism is a vital shape in geometry. The figure’s name is derived from the fact that it is created by taking into account a polygonal base and expanding its sides until it creates an equilibrium with the opposing base.

This article post will talk about what a prism is, its definition, different types, and the formulas for volume and surface area. We will also provide examples of how to utilize the data given.

## What Is a Prism?

A prism is a 3D geometric shape with two congruent and parallel faces, called bases, that take the form of a plane figure. The other faces are rectangles, and their amount depends on how many sides the similar base has. For example, if the bases are triangular, the prism would have three sides. If the bases are pentagons, there would be five sides.

### Definition

The properties of a prism are astonishing. The base and top each have an edge in common with the additional two sides, making them congruent to one another as well! This means that all three dimensions - length and width in front and depth to the back - can be deconstructed into these four parts:

A lateral face (implying both height AND depth)

Two parallel planes which make up each base

An illusory line standing upright through any given point on either side of this shape's core/midline—known collectively as an axis of symmetry

Two vertices (the plural of vertex) where any three planes join

### Types of Prisms

There are three major kinds of prisms:

Rectangular prism

Triangular prism

Pentagonal prism

The rectangular prism is a regular kind of prism. It has six faces that are all rectangles. It looks like a box.

The triangular prism has two triangular bases and three rectangular sides.

The pentagonal prism consists of two pentagonal bases and five rectangular faces. It seems almost like a triangular prism, but the pentagonal shape of the base sets it apart.

## The Formula for the Volume of a Prism

Volume is a calculation of the sum of space that an thing occupies. As an important shape in geometry, the volume of a prism is very important for your learning.

The formula for the volume of a rectangular prism is V=B*h, assuming,

V = Volume

B = Base area

h= Height

Finally, given that bases can have all kinds of shapes, you are required to learn few formulas to determine the surface area of the base. However, we will go through that later.

### The Derivation of the Formula

To obtain the formula for the volume of a rectangular prism, we are required to observe a cube. A cube is a 3D item with six faces that are all squares. The formula for the volume of a cube is V=s^3, where,

V = Volume

s = Side length

Immediately, we will have a slice out of our cube that is h units thick. This slice will make a rectangular prism. The volume of this rectangular prism is B*h. The B in the formula implies the base area of the rectangle. The h in the formula stands for height, which is how thick our slice was.

Now that we have a formula for the volume of a rectangular prism, we can generalize it to any type of prism.

### Examples of How to Use the Formula

Considering we understand the formulas for the volume of a rectangular prism, triangular prism, and pentagonal prism, let’s utilize these now.

First, let’s figure out the volume of a rectangular prism with a base area of 36 square inches and a height of 12 inches.

V=B*h

V=36*12

V=432 square inches

Now, let’s try one more problem, let’s calculate the volume of a triangular prism with a base area of 30 square inches and a height of 15 inches.

V=Bh

V=30*15

V=450 cubic inches

Considering that you possess the surface area and height, you will calculate the volume with no issue.

## The Surface Area of a Prism

Now, let’s talk regarding the surface area. The surface area of an object is the measurement of the total area that the object’s surface occupies. It is an crucial part of the formula; therefore, we must know how to calculate it.

There are a several different methods to find the surface area of a prism. To measure the surface area of a rectangular prism, you can use this: A=2(lb + bh + lh), assuming,

l = Length of the rectangular prism

b = Breadth of the rectangular prism

h = Height of the rectangular prism

To work out the surface area of a triangular prism, we will use this formula:

SA=(S1+S2+S3)L+bh

assuming,

b = The bottom edge of the base triangle,

h = height of said triangle,

l = length of the prism

S1, S2, and S3 = The three sides of the base triangle

bh = the total area of the two triangles, or [2 × (1/2 × bh)] = bh

We can also utilize SA = (Perimeter of the base × Length of the prism) + (2 × Base area)

### Example for Finding the Surface Area of a Rectangular Prism

Initially, we will work on the total surface area of a rectangular prism with the following information.

l=8 in

b=5 in

h=7 in

To figure out this, we will plug these values into the corresponding formula as follows:

SA = 2(lb + bh + lh)

SA = 2(8*5 + 5*7 + 8*7)

SA = 2(40 + 35 + 56)

SA = 2 × 131

SA = 262 square inches

### Example for Calculating the Surface Area of a Triangular Prism

To compute the surface area of a triangular prism, we will find the total surface area by ensuing identical steps as priorly used.

This prism will have a base area of 60 square inches, a base perimeter of 40 inches, and a length of 7 inches. Thus,

SA=(Perimeter of the base × Length of the prism) + (2 × Base Area)

Or,

SA = (40*7) + (2*60)

SA = 400 square inches

With this data, you should be able to work out any prism’s volume and surface area. Check out for yourself and observe how easy it is!

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