2. Transversal t intersects lines s and c. A transversal is a line that intersects two coplanar lines at two distinct points.

3. Angles 1 and 4 are alternate interior angles. Angles 2 and 3 are alternate interior angles. 12 34 5 6 7 8

4. Angles 5 and 8 are alternate exterior angles. Angles 6 and 7 are alternate exterior angles. 12 34 5 6 7 8

5. Angles 1 and 3 are same-side interior angles. Angles 2 and 4 are same-side interior angles. 12 34 5 6 7 8

6. Angles 5 and 3 are corresponding angles. Angles 6 and 4 are corresponding angles. 12 34 5 6 7 8 Angles 1 and 7 are corresponding angles. Angles 2 and 8 are corresponding angles.

7. Based on this diagram and the given measurement, find the requested angle measure. 1.If m<1=25, find m<2, m<3, & m<4. 2.If m<6=105, find m<5, m<7, & m<8. 3.If m<1=3x+20 and m<2=5x+20, find m<1, m<2, m<3, & m<4. 4.If m<6=4x+15 and m<7=8x-5, find m<5, m<6, m<7, & m<8. m<2=155; m<3=25; m<4=155 m<5=75; m<7=105; m<8=75 m<1=72.5; m<2=107.5; m<3=72.5; m<4=107.5 m<5=145; m<6=35; m<7=35; m<8=145

8. Given:  2   3 Prove:  1   2 Statements Reasons 1 2 3 a b Given Vertical angles are congruent Substitution property

9. Postulate 3-1 Corresponding Angles Postulate If a transversal intersects two parallel lines, then corresponding angles are congruent.  1   2 1 2

10. Given: a || b Prove:  2   3 Statements Reasons 1 2 3 a b Given Corresponding angles are congruent Vertical angles are congruent Substitution property

11. Theorem 3-1 Alternate Interior Angles Theorem If a transversal intersects two parallel lines, then alternate interior angles are congruent.  2   3 2 3

12. Given:  2   3 Prove: m  1+m  2=180 o Statements Reasons 1 2 3 a b Given Definition of a linear pair Substitution property

13. Theorem 3-1 Same-Side Interior Angles Theorem If a transversal intersects two parallel lines, then same-side interior angles are supplementary. m  1 + m  2 = 180 1 2

14. Find the measure of each angle if the lines are parallel.

15. Find the measure of each angle. 103 77

16. Find the measure of each angle. 85