Calculate the Face Diagonal of a 2cm Cube: Geometric Measurement Problem

Question

Shown below is a cube with edges equal to 2 cm.

What is the length of the diagonal of the cube's face shown in the figure?

222

Video Solution

Solution Steps

00:00 Find the diagonal of the cube face
00:04 Let's use the Pythagorean theorem in triangle ABD
00:11 We'll substitute appropriate values and solve for the diagonal
00:35 Let's break down the square root of 8 into square root of 4 times square root of 2
00:38 Let's calculate the square root
00:44 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the side length of the square face on the cube.
  • Step 2: Use the appropriate formula to find the diagonal of a square.
  • Step 3: Calculate using the given measurements.

Now, let's work through these steps:
Step 1: The side length of the square face on the cube is given as 2 cm.
Step 2: The formula for the diagonal d d of a square with side length s s is d=s2 d = s\sqrt{2} .
Step 3: Substituting the given side length into the formula, we get:

d=2×2 d = 2 \times \sqrt{2}

Therefore, the length of the diagonal of the cube's face is 22 2\sqrt{2} cm.

The correct multiple-choice answer that corresponds to our solution is:

  • Choice 4: 2×2 2\times\sqrt{2} cm

Therefore, the solution to the problem is 22 2\sqrt{2} cm.

Answer

2×2 2\times\sqrt{2} cm