Intermediate Geometry : How to find the length of an edge of a prism

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #1 : Prisms

The volume of a prism is  .

Given the length is  and the height is , find the width of the prism.

Possible Answers:

Correct answer:

Explanation:

The volume of a prism is length times width times height.

We are given the length is 7m and the width is 5m.

So, we plug these into our formula:

 .

We then solve for height:

 .

The height is therefore 6m. 

Example Question #2 : Prisms

Find the missing edge of the prism when its volume is .

Find_the_edge

Possible Answers:

Correct answer:

Explanation:

The goal is to find the height of the rectangular prism with the given information of its width and length. The volume of a rectangular prism is , where  is width and  is height. 

Because we're given the final volume and two of the three variables, we can substitute in the information we know and solve for the missing variable. 

Therefore, the height of the prism is .

Example Question #3 : Prisms

A rectangular prism has a volume of  cubic meters. Its length is twice its width, and its height is twice its length. What is the length of the prism?

Possible Answers:

Correct answer:

Explanation:

If we let  be the width of our prism, then since the length is twice the width, our length would be .  Since the height is twice the length, our height would be .

Since the volume of a rectangular prism is simply the product of width, length, and height, we get

We then simply solve for the width.

Therefore, our width is 3.  Since our length is twice the width, the length is 6.

Example Question #4 : Prisms

A right, rectangular prism has a volume of  cubic inches. Its width is  inches and its height is  inches. What is its length?

Possible Answers:

None of the other answers.

Correct answer:

Explanation:

The formula for the volume of a right, rectangular prism is , so substitute the known values and solve for lenght.  

.  So the length is 8 inches.

Example Question #5 : Prisms

The surface area of a right rectangular prism is  square cm. Its length is  cm and its height is  cm. Find the width of the prism.

Possible Answers:

 

None of the other answers.

Correct answer:

 

Explanation:

Use the formula for finding the surface area of a right, rectangular prism,

and substitute the known values, and then solve for w.

So, 

So, the width is 7 cm.

Example Question #6 : Prisms

The height of a retangular prism is three times its width; its length is twice its width. Its surface area is 1,078 square inches. Give the width of the box.

Possible Answers:

Correct answer:

Explanation:

Since the length of the box is twice the width and the height is three times the width,  and 

The surface area of the box is

To find the width:

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