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