Statements Reason
1. [tex]\angle A[/tex] and [tex]\angle B[/tex] are supplementary Given
2. [tex]m \angle A + m \angle B = 180^\circ[/tex] Def of supplementary angles
3. [tex]m \angle A = 90^\circ[/tex] Given
4. [tex]90^\circ + m \angle B = 180^\circ[/tex] Substitution property of Equality
5. [tex]m \angle B = 90^\circ[/tex] Subtraction property of Equality
6. [tex]m \angle A = m \angle B[/tex] Substitution property of Equality
7. [tex]\angle A \cong \angle B[/tex] Angle congruence postulate
When the measures of two angles are equal, then the angles are congruent by Angle congruence postulate.
