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

A prism is a crucial figure in geometry. The figure’s name is originated from the fact that it is created by considering a polygonal base and extending its sides as far as it intersects the opposite base.

This article post will take you through what a prism is, its definition, different types, and the formulas for volume and surface area. We will also take you through some examples of how to employ the details given.

## What Is a Prism?

A prism is a 3D geometric figure with two congruent and parallel faces, well-known as bases, that take the form of a plane figure. The other faces are rectangles, and their count relies on how many sides the identical 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 fascinating. The base and top both have an edge in common with the other two sides, creating them congruent to one another as well! This implies that every three dimensions - length and width in front and depth to the back - can be broken down into these four parts:

A lateral face (meaning both height AND depth)

Two parallel planes which make up each base

An fictitious line standing upright across any provided point on either side of this shape's core/midline—also 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 sides that are all rectangles. It looks like a box.

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

The pentagonal prism comprises of two pentagonal bases and five rectangular faces. It appears a lot like a triangular prism, but the pentagonal shape of the base makes it apart.

## The Formula for the Volume of a Prism

Volume is a measurement of the total amount of area that an thing occupies. As an crucial shape in geometry, the volume of a prism is very important for your studies.

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

V = Volume

B = Base area

h= Height

Ultimately, given that bases can have all types of shapes, you will need to know a few formulas to figure out the surface area of the base. However, we will touch upon that afterwards.

### The Derivation of the Formula

To derive the formula for the volume of a rectangular prism, we have to look at a cube. A cube is a three-dimensional object with six sides 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 create a rectangular prism. The volume of this rectangular prism is B*h. The B in the formula stands for the base area of the rectangle. The h in the formula implies the height, that is how dense 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 Utilize the Formula

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

First, let’s calculate 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, consider one more problem, let’s work on 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 figure out the volume with no issue.

## The Surface Area of a Prism

Now, let’s talk about the surface area. The surface area of an item is the measurement of the total area that the object’s surface occupies. It is an essential part of the formula; consequently, we must learn how to calculate it.

There are a few distinctive methods to work out the surface area of a prism. To figure out the surface area of a rectangular prism, you can utilize this: A=2(lb + bh + lh), where,

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 Computing the Surface Area of a Rectangular Prism

Initially, we will figure out the total surface area of a rectangular prism with the following dimensions.

l=8 in

b=5 in

h=7 in

To solve this, we will replace these numbers 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 Computing the Surface Area of a Triangular Prism

To calculate the surface area of a triangular prism, we will find the total surface area by ensuing similar 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. Hence,

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 figure out any prism’s volume and surface area. Try it out for yourself and observe how simple it is!

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