Question

A cube. The top face has points C, A, B, D and the bottom face has points G, E, F, H.
Which are right triangles that can be formed using a diagonal through the interior of the cube? Select all that apply.
Triangle CEG
Triangle AEH
Triangle CFG
Triangle BCH
Triangle BFG
Triangle DEG

Answers

GPT-4o mini
In a cube, a diagonal connects two opposite vertices. For a triangle formed with a diagonal of the cube to be a right triangle, it must include one of the endpoints of the diagonal as well as two other vertices forming a right angle at one of the points.

Let's analyze the triangles formed with the cube's vertices and the diagonals:

1. **Diagonal CEG** connects points C and G.
- Triangle **CEG** is formed by points C, E, and G.
- There is a right angle between C and E (since they are both in the same plane at the top and bottom faces, respectively). So, **Triangle CEG** is a right triangle.

2. **Diagonal AEH** connects points A and H.
- Triangle **AEH** consists of points A, E, and H.
- The right angle occurs between A and H. Thus, **Triangle AEH** is also a right triangle.

3. **Diagonal CFG** connects points C and F.
- Triangle **CFG** consists of points C, F, and G.
- Here, no right angle is formed, both C and G are on opposite vertical planes that do not contribute to a right angle. Thus, **Triangle CFG** is not a right triangle.

4. **Diagonal BCH** connects points B and H.
- Triangle **BCH** consists of points B, C, and H.
- B and C can form a right angle on the face of the cube, but since H connects vertically, it does not create a right triangle. Thus, **Triangle BCH** is not a right triangle.

5. **Diagonal BFG** connects points B and G.
- Triangle **BFG** consists of points B, F, and G.
- B and G can connect, but F does not maintain any right angle with them. Thus, **Triangle BFG** is not a right triangle.

6. **Diagonal DEG** connects points D and G.
- Triangle **DEG** consists of points D, E, and G.
- There is no right angle formed. Therefore, **Triangle DEG** is not a right triangle.

After analyzing all the triangles with respect to the diagonals of the cube, the following right triangles can indeed be formed:

- Triangle CEG
- Triangle AEH

So, the correct answer is **Triangle CEG** and **Triangle AEH**.