Question

problem 10: select the altitude of △abc from vertex b.

Explanation:

Step1: Recall altitude definition

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

Step2: Identify opposite side

For vertex B of $\triangle ABC$, the opposite side is AC.

Step3: Look for perpendicular line

We need to find the option that shows a line starting from B and perpendicular to AC.

Answer:

The altitude from vertex B of $\triangle ABC$ is the line segment that is perpendicular to the opposite - side (in this case, side AC) and has an endpoint at B. Without seeing the actual options for A, C, D, E, if we assume the correct option shows a line segment starting from B and perpendicular to AC.