Question

(a) one pair of angles that form a linear pair (b) one pair of vertical angles (c) one pair of angles that are supplementary (a) linear pair: ∠ and ∠ (b) vertical angles: ∠ and ∠ (c) supplementary angles: ∠ and ∠ try again

Explanation:

Step1: Recall linear - pair definition

A linear pair of angles are adjacent angles that form a straight - line. $\angle1$ and $\angle2$ are adjacent and their non - common sides form a straight line.

Step2: Recall vertical - angles definition

Vertical angles are the non - adjacent angles formed by two intersecting lines. $\angle1$ and $\angle3$ are vertical angles as they are formed by the intersection of lines $l$ and $n$.

Step3: Recall supplementary - angles definition

Supplementary angles are two angles whose sum is $180^{\circ}$. A linear pair of angles is always supplementary. So, $\angle1$ and $\angle2$ are supplementary.

Answer:

(a) $\angle1$ and $\angle2$
(b) $\angle1$ and $\angle3$
(c) $\angle1$ and $\angle2$