Based on the provided proof structure for demonstrating that the sum of the measures of the exterior angles of a triangle is 360°, here's how you can fill in the blanks in step 2:
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Consider a triangle with interior angles ∠2, ∠5, and ∠3 and corresponding exterior angles ∠1, ∠4, and ∠6.
Reason: Given -
\( m∠1 + m∠2 = 180° \)
\( m∠4 + m∠5 = 180° \)
\( m∠6 + m∠3 = 180° \)
Reason: Definition of Linear Pairs -
\((m∠1 + m∠2) + (m∠4 + m∠5) + (m∠6 + m∠3) = 180° + 180° + 180° \)
Reason: Addition -
\((m∠2 + m∠3 + m∠5) + (m∠1 + m∠4 + m∠6) = 540° \)
Reason: Rearrange and simplify -
\(m∠2 + m∠3 + m∠5 = 180° \)
Reason: Triangle Angle Sum Theorem -
\(180° + (m∠1 + m∠4 + m∠6) = 540° \)
Reason: Substitution -
\((m∠1 + m∠4 + m∠6) = 360° \)
Reason: Subtraction Property of Equality
This completed proof shows that the exterior angles add up to 360° by utilizing the properties of linear pairs and the triangle angle sum theorem.