Geometry

Question Analysis

This question focuses on using the definition of an altitude in a triangle to determine the measure of an angle. The key is to recall the property that an altitude is perpendicular to the opposite side.

Key Concept Explanation

An altitude of a triangle is a line segment drawn from a vertex perpendicular to the opposite side (or the line containing the opposite side). By the definition of perpendicular lines, the angle formed between two perpendicular lines is .

Step - by - Step Solution

1. Recall the property of an altitude:

Since  is an altitude of , it means  is perpendicular to  (in this case, the extension of  to include point