Interior vs Exterior Math Example 3

Follow the full solution, then compare it with the other examples linked below.

Example 3

easy
A triangle is drawn on paper. Point PP is inside the triangle and point QQ is outside. If you draw a straight line from PP to QQ, how many times must it cross the boundary of the triangle?

Solution

  1. 1
    Step 1: Visualize a path from an interior point PP to an exterior point QQ. To travel from inside to outside, you must pass through the boundary at least once.
  2. 2
    Step 2: For a convex shape like a triangle, a straight line segment from an interior point to an exterior point crosses the boundary exactly once.

Answer

Exactly once.
This is a fundamental property of boundaries: any path connecting an interior point to an exterior point must cross the boundary at least once. For a convex shape and a straight-line path, it crosses exactly once. This idea is central to understanding what a boundary separates.

About Interior vs Exterior

Interior consists of points strictly inside a boundary; exterior consists of points strictly outside the boundary.

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More Interior vs Exterior Examples