The missing statements and reasons to proof that ∠1 is supplementary to ∠3 are:
Thus, to prove that ∠1 is supplementary to ∠3:
We are given that lines m and n are parallel.
∠1 and ∠3 are corresponding angles.
So therefore, ∠1 = ∠3 by the corresponding angles postulate.
∠2 and ∠3 are linear pair, their sum therefore equals 180° based on the definition of supplementary angles.
Based on the substitution property, we have the following:
m∠2 + m∠3 = m∠1 + m∠3
m∠1+m∠3=180°
Therefore, ∠1 is supplementary to ∠3 based on the definition of supplementary.
The missing statements and reasons to proof that ∠1 is supplementary to ∠3 are:
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