Geometry

Question Analysis

This question focuses on using the definition of an altitude in a triangle to find the measure of an angle. The key is to recall the property of an altitude being 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 perpendicularity, when two lines are perpendicular, the angle between them is .

Step - by - Step Solution

1. Recall the property of an altitude:

Since  is an altitude of , it means  is perpendicular to .

2. Determine the measure of