Intermediate Geometry : Prisms

Study concepts, example questions & explanations for Intermediate Geometry

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Example Questions

Example Question #3 : How To Find The Diagonal Of A Prism

A right, rectangular prism has a length of  meters, width that is  meters longer than the length, and a height of  meters. The volume of the prism is  cubic meters. Find the diagonal of the prism.

Possible Answers:

None of the other answers.

Correct answer:

Explanation:

First, use the volume formula,

 to find the missing length and width.  

Since  cannot be a negative value is it represents a length of a prism, we know .  So the length is 2 meters, and therefore the width is 5 meters.  

Now you can plug in the length, width and height into the formula for finding the diagonal of the prism.

 .

Example Question #4 : How To Find The Diagonal Of A Prism

A right, rectangular prism has a volume of  cubic centimeters.  Its width is  cm and its length is three times its height. Find the length of the diagonal of the prism.

Possible Answers:

None of the other answers.

Correct answer:

Explanation:

First, use the volume to find the missing height and length.  

Since the length is three times the height, use  to represent the length and  to represent the height.  

So, .  

So the height of the prism is 2 centimeters, and the length is 6 centimeters.

Use these values to now solve for the diagonal distance.  

.

Example Question #2 : How To Find The Diagonal Of A Prism

The surface area of a right, rectangular prism is  square inches.  The height is  inches and the length is  times the width. Find the diagonal distance of the prism.

Possible Answers:

None of the other choices.

Correct answer:

Explanation:

Use the surface area, 280 square inches, and the formula for finding the surface area of a right, rectangular prsim  to find the missing length and width measurements.  

So, 

Since  represents the length of a solid figure, we must assume , rather than the negative value.  

So, the width of the figure is 2 inches and the length is 10 inches.

Now, use the formula for finding the diagonal of a right, rectangular prism:

.

Example Question #1 : How To Find The Diagonal Of A Prism

A right, rectangular prism has a surface area of  square meters. Its width is twice its length, and its height is four times its length. Find the diagonal distance of the prism.

Possible Answers:

None of the other answers.

Correct answer:

Explanation:

Use the surface area of the prism to find the missing length, width and height.

So, the prism's length is 1 meter, the width is 2 meters and the height is 4 meters.  

Now you can find the diagonal distance using those values.  

.

Example Question #1 : How To Find The Diagonal Of A Prism

Cube

The above cube has edges of length 1. True or false: The dashed line has length .

Possible Answers:

True

False

Correct answer:

False

Explanation:

Examine the diagram below.

Cube

 is a right triangle with legs of length , so it is an isosceles - or 45-45-90 - right triangle. By the 45-45-90 Triangle Theorem its hypotenuse measures

 is a right triangle with legs of lengths  and , so the length of its hypotenuse is

.

, the diagonal in question, has length , not .

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