Math Problem Statement

This diagram shows a cube. Each edge of the cube is 6 units long. The diagonal of each face is x units long. The diagonal of the cube is y units long. Find x and y. If necessary, round your answers to the nearest tenth.

Solution

The problem involves finding the diagonals of a cube:

  1. xx is the diagonal of one face of the cube.
  2. yy is the diagonal of the entire cube.

Let’s solve this step by step:


Step 1: Finding xx (Diagonal of one face)

The diagonal xx of a square face can be found using the Pythagorean Theorem:

x=a2+a2=2a2x = \sqrt{a^2 + a^2} = \sqrt{2a^2}

Here a=6a = 6 (edge length of the cube):

x=2(62)=728.5units.x = \sqrt{2(6^2)} = \sqrt{72} \approx 8.5 \, \text{units.}


Step 2: Finding yy (Diagonal of the cube)

To find the diagonal yy of the entire cube, we apply the Pythagorean Theorem again. The diagonal yy forms a right triangle with two sides:

  • One is the edge of the cube (a=6a = 6).
  • The other is the diagonal of the face (x=8.5x = 8.5).

y=x2+a2=(8.5)2+62y = \sqrt{x^2 + a^2} = \sqrt{(8.5)^2 + 6^2}

Calculate step-by-step: y=72.25+36=108.2510.4units.y = \sqrt{72.25 + 36} = \sqrt{108.25} \approx 10.4 \, \text{units.}


Final Answer:

  • x8.5x \approx 8.5 units
  • y10.4y \approx 10.4 units

Would you like a breakdown of the calculations or further clarification?


Here are 5 related questions to deepen your understanding:

  1. How would the calculations change if the cube's edge length was different?
  2. What is the formula for the diagonal of a face in terms of edge length?
  3. How is the 3D diagonal yy generalized for cubes with edge length aa?
  4. Can we solve this problem using vector geometry instead of the Pythagorean theorem?
  5. What are real-life applications of calculating 3D diagonals in cubes?

Tip: Always visualize the 3D problem step by step to ensure clarity when applying the Pythagorean theorem in multiple dimensions.

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Math Problem Analysis

Mathematical Concepts

Geometry
Pythagorean Theorem
3D Spatial Reasoning

Formulas

x = √(a² + a²)
y = √(x² + a²)

Theorems

Pythagorean Theorem

Suitable Grade Level

Grades 8-10