1. Proving Lines are Parallel
Unit 3: Day 2.
Proving Lines are Parallel

2. Check Your Skills a ll b If m<2 = 45 Find m<6
If m<1 = 2x + 4 and m<5= 3x – 8. Find the m<1.

3. Homework Check

4.
4. x=10, m<3 = 80
5. x=47, m<3= 91
6.a) 1&8, 4&7, 2&5, or 3&6
b) 4&5 or 3&8
c) 4&8, 3&5

5. Proving Lines Parallel
Ways to Prove Lines are ll:
If corresponding <‘s are
If Alternate Interior <s are
If Alternate Exterior <s are
If Same-Side Interior <s are supplementary
If Same-Side Exterior <s are supplementary

6. Corresponding Angle Postulate If a transversal intersects two parallel lines, then corresponding angles are congruent. Converse of the Corresponding Angle Postulate: If two lines and a transversal form corresponding angles that are congruent, then the two lines are parallel. True

7. Alternate Interior Angles Theorem: If a transversal intersects two parallel lines, then alternate interior angles are congruent Converse of Alt. Int. <s Theorem: If two lines and a transversal form alt. int. <s that are congruent, then the two lines are parallel.

8. Same-Side Interior Angle Theorem: If a transversal intersects two parallel lines, then same-side interior angles are supplementary Converse of Same-Side Int. < theorem: If two lines and a transversal form same-side interior angles that are supplementary, then the two lines are parallel.

9. Are the lines ll? Justify.

16. Homework: ClassWork Lesson 3-2 Proving Lines Parallel
Examples 1-4 and the 4 problems without #’s
Need to be checked off for a grade.
Homework:
Remainder of worksheet