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

A prism is a vital figure in geometry. The shape’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 blog post will discuss what a prism is, its definition, different kinds, and the formulas for surface areas and volumes. We will also give examples of how to use the information given.

## What Is a Prism?

A prism is a 3D geometric shape with two congruent and parallel faces, known as bases, that take the shape of a plane figure. The other faces are rectangles, and their number rests 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 will be five sides.

### Definition

The characteristics of a prism are interesting. The base and top both have an edge in parallel with the other two sides, making them congruent to each other as well! This means that every three dimensions - length and width in front and depth to the back - can be deconstructed into these four parts:

A lateral face (signifying both height AND depth)

Two parallel planes which make up each base

An imaginary line standing upright through any provided point on either side of this shape's core/midline—usually 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 matches the looks of a box.

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

The pentagonal prism has two pentagonal bases and five rectangular faces. It appears 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 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 learning.

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

V = Volume

B = Base area

h= Height

Finally, since bases can have all sorts of figures, you will need to know a few formulas to calculate 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 have to observe a cube. A cube is a three-dimensional object with six faces that are all squares. The formula for the volume of a cube is V=s^3, assuming,

V = Volume

s = Side length

Immediately, we will take 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 implies the base area of the rectangle. The h in the formula implies the height, which 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 Use the Formula

Since we understand the formulas for the volume of a rectangular prism, triangular prism, and pentagonal prism, now let’s use them.

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, let’s try one more problem, let’s figure out 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 problem.

## The Surface Area of a Prism

Now, let’s discuss regarding the surface area. The surface area of an item is the measurement of the total area that the object’s surface consist of. It is an crucial part of the formula; thus, we must understand how to calculate it.

There are a few varied ways to find the surface area of a prism. To calculate the surface area of a rectangular prism, you can utilize 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 compute the surface area of a triangular prism, we will employ 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 use 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 determine the total surface area of a rectangular prism with the following data.

l=8 in

b=5 in

h=7 in

To solve this, we will put these numbers into the respective 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 Finding the Surface Area of a Triangular Prism

To compute the surface area of a triangular prism, we will figure out the total surface area by ensuing same steps as earlier.

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 will be able to compute any prism’s volume and surface area. Try it out for yourself and observe how easy it is!

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