Find the Space Diagonal Formula: Expressing Length in Terms of x, y, and z

Question

Look at the rectangular prism in the figure.

Express the length of the diagonal in terms of x, y, and z.

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Video Solution

Solution Steps

00:06 Let's express the diagonal of the box using its dimensions.
00:11 Each face of the box is a rectangle, so all the angles are right angles.
00:17 Now, we'll use the Pythagorean Theorem in triangle E H G to find the length of E G.
00:24 This gives us the expression for the diagonal of face E G.
00:28 Remember, in rectangles, opposite sides are equal. So, each face in the box maintains this property.
00:38 There's a right angle here because a perpendicular to a face is perpendicular to any line going through it.
00:44 Next, use the Pythagorean Theorem in triangle E G C to find the length of E C.
00:53 Let's substitute the value of E G that we previously found.
01:01 Go ahead and take the square root.
01:08 And that's how we solve this problem!

Step-by-Step Solution

To solve for the diagonal of a rectangular prism with dimensions xx, yy, and zz, we'll utilize the Pythagorean theorem in three dimensions. This enables us to account for the three different sides of the prism.

Let us break this down into steps:

  • Step 1: Identify the dimensions given: length xx, width yy, and height zz.
  • Step 2: Recognize that the diagonal stretches across the prism from one corner to the opposite corner, forming a 3D hypotenuse.
  • Step 3: Apply the formula for the diagonal of a rectangular prism:
Diagonal=x2+y2+z2 \text{Diagonal} = \sqrt{x^2 + y^2 + z^2}

This formula arises because the diagonal spans across the 3D space of the prism. By applying the Pythagorean theorem first to the base rectangle and then incorporating the height, we account for all dimensions of the prism.

Thus, the length of the diagonal is given by x2+y2+z2 \sqrt{x^2 + y^2 + z^2} .

Answer

x2+y2+z2 \sqrt{x^2+y^2+z^2}