1. j || k and angle 1 = angle 3. 1. Given
(Those are the givens, no surprise there.)
2. angle 1 = angle 2. 2. If the lines are ||, then corresponding angles are congruent
j and k are parallel, l transverse so 1 and 2 are congruent corresponding angles.
3. angle 2 = angle 3 3. Substitution
We substitute angle 2 in for angle 1 in the other equation. This might also be called the transitivity of equality.
4. l || m 4. If alternate interior angles ...
We have congruent alternate interior angles of a transversal, so parallel lines.
Answers: 2 1 4 3
