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. Vertical angle theorem
3. Angle congruence postulate
4. Given
5. <u> Substitution Property of Equality</u>
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,
6. ∠JNL is a right angle. Definition of right angle