Question

problem 10: select the altitude of △abc from vertex b. (first taught in lesson 41)

Explanation:

Step1: Recall altitude definition

The altitude of a triangle from a vertex is a line segment drawn from that vertex perpendicular to the opposite side.

Step2: Identify opposite side

For vertex B of $\triangle ABC$, the opposite side is AC. So the altitude from B is the perpendicular from B to AC.

Answer:

The altitude from vertex B of $\triangle ABC$ is the perpendicular line segment from vertex B to the opposite - side (AC or its extension).