Answer:
3. Median
4. Altitude
Step-by-step explanation:
A median is a line segment that connects a triangle's vertex with the midpoint of the opposite side. AB in problem 3 is a median.
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An altitude is a line segment that connects a triangle's vertex with the nearest point on the opposite side (or its extension). The altitude is perpendicular to the side opposite the vertex. AB in problem 4 is an altitude.
