Geometry

Question Analysis

This question focuses on testing the understanding of the definition of an altitude in a triangle. The main task is to correctly identify the option that accurately describes what an altitude is among the given choices.

Key Concept Explanation

An altitude of a triangle is a line segment that starts from a vertex of the triangle and is perpendicular to the opposite side (or to the line that contains the opposite side). This perpendicularity is the key characteristic of an altitude.

Step - by - Step Solution

A: The length of the longest side of the triangle has nothing to do with the concept of an altitude. An altitude is not related to the length of the longest side. So, this option is incorrect.

B: The angle formed by two sides of the triangle is not an altitude. An altitude is a line segment, not an angle. So, this option is incorrect.

C: A line segment drawn from a vertex to the mid - point of the opposite side is called a median, not an altitude. So, this option is incorrect.

D: This option correctly states that an altitude is a line segment drawn from a vertex perpendicular to the opposite side or to the line containing the opposite side. So, this option is correct.

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