Given: ∠JNL and ∠MNK are vertical angles and m∠MNK=90°
Prove: ∠JNL is a right angle.
Statements Reasons
1. ∠JNL and ∠MNK are vertical angles. Given
2. [tex]\angle JNL \cong \angle MNK[/tex] Vertical angle theorem
3. [tex]m \angle JNL = m \angle MNK[/tex] Angle congruence postulate
4. [tex]m \angle MNK = 90^\circ[/tex] Given
5. [tex]m \angle JNL = 90^\circ[/tex] Substitution Property of Equality
Since, the measures of angle JNL and MNK are equal and the measure of angle MNK is 90 degrees. therefore, by substitution property of equality, both the angles JNL and MNK will have an equal measure.
Therefore, [tex]m \angle JNL = 90^\circ[/tex]
6. ∠JNL is a right angle. Definition of right angle
