Calculate the Diagonal of a Rectangular Prism: Dimensions 5x, x+3, 2x+1

Question

A rectangular prism has dimensions of 5x,x+3,2x+1 5x,x+3,2x+1 .

Calculate the length of its diagonal.

5X5X5X2X+12X+12X+1X+3X+3X+3AAABBBCCCDDDAAA111BBB111CCC111DDD111

Video Solution

Solution Steps

00:00 Calculate the length of the box diagonal
00:03 Use the Pythagorean theorem in triangle C1CB to find C1B
00:16 Substitute appropriate values according to the given data and solve for BC1
00:26 Open parentheses properly
00:37 Collect terms
00:45 Draw the face diagonal
00:51 Now use the Pythagorean theorem in triangle ABC1 to find AC1
01:01 Substitute appropriate values according to the given data and solve for AC1
01:17 Collect terms
01:34 And this is the solution to the question

Step-by-Step Solution

To solve for the diagonal of the rectangular prism, we apply the three-dimensional Pythagorean theorem.

The formula for the diagonal dd of a rectangular prism with side lengths aa, bb, and cc is:

d=a2+b2+c2 d = \sqrt{a^2 + b^2 + c^2}

Substituting the given dimensions into the formula, we get:

a=5x a = 5x , b=x+3 b = x + 3 , c=2x+1 c = 2x + 1

Therefore, the expression for the diagonal becomes:

d=(5x)2+(x+3)2+(2x+1)2 d = \sqrt{(5x)^2 + (x+3)^2 + (2x+1)^2}

Calculating each squared term:

  • (5x)2=25x2 (5x)^2 = 25x^2
  • (x+3)2=x2+6x+9 (x+3)^2 = x^2 + 6x + 9
  • (2x+1)2=4x2+4x+1 (2x+1)^2 = 4x^2 + 4x + 1

Add these results together:

25x2+x2+6x+9+4x2+4x+1 25x^2 + x^2 + 6x + 9 + 4x^2 + 4x + 1

Simplify the expression:

  • 25x2+x2+4x2=30x2 25x^2 + x^2 + 4x^2 = 30x^2
  • 6x+4x=10x 6x + 4x = 10x
  • 9+1=10 9 + 1 = 10

Thus, the expression inside the square root becomes:

30x2+10x+10 30x^2 + 10x + 10

Finally, the length of the diagonal is:

d=30x2+10x+10 d = \sqrt{30x^2 + 10x + 10}

Therefore, the solution to the problem is 30x2+10x+10\sqrt{30x^2 + 10x + 10}.

Answer

30x2+10x+10 \sqrt{30x^2+10x+10}