Using the Pythagorean Theorem in Cuboids: Using Pythagoras' theorem to calculate the height of a box

Examples with solutions for Using the Pythagorean Theorem in Cuboids: Using Pythagoras' theorem to calculate the height of a box

Exercise #1

Look at the rectangular prism in the figure below.

The length of the diagonal is 214 2\sqrt{14} cm.

Calculate BB1 BB^1 .

444666AAABBBCCCDDDA1A1A1B1B1B1C1C1C1

Video Solution

Step-by-Step Solution

The problem asks us to find the height of a rectangular prism. Given the space diagonal d=214 d = 2\sqrt{14} cm and base dimensions (length = 6 cm, width = 4 cm), we can use the formula for the space diagonal:

d=l2+w2+h2 d = \sqrt{l^2 + w^2 + h^2}

Substitute the known values:

214=62+42+h2 2\sqrt{14} = \sqrt{6^2 + 4^2 + h^2}

First, calculate 62+42 6^2 + 4^2 :

62=36,42=16 6^2 = 36, \quad 4^2 = 16

Thus, 62+42=52 6^2 + 4^2 = 52 .

Substitute back into the equation:

(214)2=52+h2 (2\sqrt{14})^2 = 52 + h^2

Calculate (214)2 (2\sqrt{14})^2 :

22×(14)2=4×14=56 2^2 \times (\sqrt{14})^2 = 4 \times 14 = 56

Substitute and solve for h2 h^2 :

56=52+h2 56 = 52 + h^2

Subtract 52 from both sides:

h2=4 h^2 = 4

Take the square root of both sides:

h=4=2 h = \sqrt{4} = 2

Therefore, the height of the rectangular prism BB1 BB^1 is 2 2 cm.

Answer

2 2

Exercise #2

Look at the rectangular prism in the figure below.

Calculate AD.

999131313AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

222 2\sqrt{22} cm

Exercise #3

Look at the orthohedron in the figure.

A1B=12 A^1B=12

Canculate CC1 CC^1 .

101010121212AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

211 2\sqrt{11}

Exercise #4

ABCDA1B1C1D1 ABCDA^1B^1C^1D^1 is a rectangular prism.


D1C1=14 D^1C^1=14

BD=20 BD=20

Calculate the height of the rectangular prism.

141414202020AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

251 2\sqrt{51} cm

Exercise #5

Look at the rectangular prism below.

ABCDA1B1C1D1 ABCDA^1B^1C^1D^1

BC1=12 BC^1=12

D1D=10 D^1D=10

D1C=7 D^1C=7

Calculate AD.

101010121212777AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

211 2\sqrt{11} cm

Exercise #6

A rectangular prism has a diagonal length of 230 2\sqrt{30} cm.

It is 4 4 cm high and 2 2 cm wide.

Calculate the length of the rectangular prism.

222444AAAEEECCCBBBDDD

Video Solution

Answer

10 10 cm

Exercise #7

Look at the rectangular prism in the figure below and calculate CC1 CC^1 .

444131313181818AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

139 \sqrt{139} cm

Exercise #8

Look at the rectangular prism in the figure below.

Calculate the length of DD1 DD^1 .

111111777AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

62 6\sqrt{2} cm

Exercise #9

Look at the orthohedron in the figure below.

BC1=2AA1 BC^1=2AA^1
A1D1=5 A^1D^1=5

Calculate AA1 AA^1 .

555AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

53 \frac{5}{\sqrt{3}} cm

Exercise #10

Look at the orthohedron in the figure below.

Calculate DE DE .

777141414AAABBBCCCDDDEEEFFFGGG

Video Solution

Answer

It is not possible to calculate.

Exercise #11

ABCDA1B1C1D1 ABCDA^1B^1C^1D^1 is an orthohedron.

BC1=2x BC^1=2x

A1D1=3y A^1D^1=3y

Express BB1 BB^1 in terms of x and y.

3Y3Y3Y2X2X2XAAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

4x29y2 \sqrt{4x^2-9y^2}

Exercise #12

Look at the rectangular prism below and calculate BC BC .

666333252525AAABBBCCCDDDEEEFFFGGGHHH

Video Solution

Answer

2145 2\sqrt{145}

Exercise #13

Look at the rectangular prism in the figure below.

The diagonal is 13x 13x long.

A1D1=2y A^1D^1=2y

A1B1=2x A^1B^1=2x

Calculate DD1 DD^1 .

2X2X2X2Y2Y2Y13X13X13XAAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

165x24y2 \sqrt{165x^2-4y^2}

Exercise #14

A rectangular prism has a diagonal length of 24 cm.

The surface area of one of the faces is 40 cm² and its side measures 4 cm.

Calculate the dimensions of the rectangular prism.

S=40S=40S=40444242424AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

10,4,2115 10,4,2\sqrt{115}

Exercise #15

Look at the orthohedron below.

B1C1=7x B^1C^1=7x

DC=4x DC=4x

BD1=226x BD^1=2\sqrt{26}x

Calculate AA1 AA^1 .

4X4X4X7X7X7XAAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Answer

x39 x\sqrt{39}