Inactive Tutor answered 03/30/23
Vertical angles are the opposite angles formed by two intersecting lines,
and they are always equal in measurement.
Thus, the vertical angles, <1 and <2, are congruent. (<1 ≅ <2)
Complementary angles are angles that add up to 90º.
Thus, <2 + <3 = 90º.
Since <1 = 71° and <1 = <2, <2 is also 71°.
Substitute <2 with 71° in the equation <2 + <3 = 90º:
71° + <3 = 90°
Subtract 71° from both sides of the above equation:
<3 = 90° - 71° = 19°
Therefore, the measurement of <3 is 19°.