Answer:
angle 1 and angle 3 are congruent
Step-by-step explanation:
Angles supplementary to the same angle are congruent. Here both angles 1 and 3 are supplementary to angle 2, so angles 1 and 3 are congruent.
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If you like, you can get there algebraically:
m∠1 + m∠2 = 180
m∠3 + m∠2 = 180
Subtract the second equation from the first:
(m∠1 + m∠2) - (m∠3 + m∠2) = (180) - (180)
m∠1 -m∠3 = 0 . . . . simplify
m∠1 = m∠3 . . . . . . add m∠3
When angle measures are the same, the angles are congruent.
∠1 ≅ ∠3
