Question

(a) name the sides of ∠abc. and (b) write two other names for ∠2. and (c) name the vertex of ∠1.

Explanation:

Step1: Recall angle - side relationship

An angle is formed by two rays with a common endpoint. For $\angle ABC$, the sides are the two rays that form the angle.
The sides of $\angle ABC$ are $\overrightarrow{BA}$ and $\overrightarrow{BC}$.

Step2: Recall angle - naming conventions

An angle can be named in different ways. $\angle 2$ can also be named as $\angle CBD$ (using three - point naming with the vertex in the middle) and $\angle DBC$ (also a three - point naming with the vertex in the middle).

Step3: Recall vertex definition

The vertex of an angle is the common endpoint of the rays that form the angle. For $\angle 1$, the vertex is point $B$.

Answer:

(a) $\overrightarrow{BA}$, $\overrightarrow{BC}$
(b) $\angle CBD$, $\angle DBC$
(c) $B$