Counting Perpendicular Lines in a Cube: Verifying the 24 Pairs Property

Perpendicular Lines with Cube Face Analysis

Are there 24 pairs of perpendicular lines in a cube?

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Step-by-step video solution

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00:00 Are there 24 perpendiculars in a cube?
00:03 A perpendicular creates a right angle at the intersection point between lines
00:07 Let's mark and count all right angles to find the perpendiculars
00:09 We have 4 perpendiculars in each face
00:15 Let's count the number of faces we have and multiply by the number of perpendiculars
00:22 The fourth face at the bottom is not visible in the drawing
00:28 The back face is also not visible
00:31 As well as the left face
00:34 Let's multiply the number of faces we have (6) by the number of perpendiculars (4)
00:38 And that's the solution to the question

Step-by-step written solution

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1

Understand the problem

Are there 24 pairs of perpendicular lines in a cube?

2

Step-by-step solution

Remember that perpendicular lines form a 90-degree angles.

As we know, in the cube all angles are 90 degrees (right angles).

We will mark the angles of the highlighted face in the following way:

As a cube has 6 faces, we will multiply the number of angles we marked by 6 to get:

4×6=24 4\times6=24

Therefore, the number of perpendicular lines in a cube is 24.

3

Final Answer

Yes

Key Points to Remember

Essential concepts to master this topic
  • Definition: Perpendicular lines meet at exactly 90-degree angles
  • Counting Method: Count 4 right angles per face: 4×6=24 4 \times 6 = 24
  • Verification: Each cube face has exactly 4 corner angles all measuring 90° ✓

Common Mistakes

Avoid these frequent errors
  • Counting edges instead of perpendicular line pairs
    Don't count the 12 edges of the cube = only gets edge count! Edges are line segments, not the perpendicular relationships between lines. Always count the 90-degree angle formations at each face corner.

Practice Quiz

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What do the four figures below have in common?

1234

FAQ

Everything you need to know about this question

What exactly makes two lines perpendicular?

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Two lines are perpendicular when they intersect at exactly 90 degrees. In a cube, every corner where two edges meet forms this perfect right angle!

Why do we multiply 4 by 6?

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Each face of the cube has 4 corner angles that are 90 degrees. Since a cube has 6 faces, we get: 4×6=24 4 \times 6 = 24 total perpendicular line pairs.

Are we counting the same perpendicular lines multiple times?

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No! Each 90-degree angle represents a unique pair of perpendicular lines. The faces don't share the same corner angles, so each count is distinct.

How can I visualize this better?

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Look at any corner of a box or room! You'll see three edges meeting at right angles. Each cube face contributes 4 such corners, giving us our 24 total perpendicular pairs.

Does this work for other 3D shapes?

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Only for shapes with right angles! A sphere has no perpendicular lines, while a rectangular prism would also have 24 (if all angles are 90°).

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