1. Properties of Parallel Lines Learning Target: I can use properties of parallel lines to find angle measures.

2. A transversal is a line that intersects two coplanar lines at two different points. When a transversal intersects those two lines it creates eight angles. 1 2 3 4 5 6 7 8

3. · Inside the two parallel lines ·Opposite sides of the transversal ·Examples 3 & 6 4 & 5 Alternate Interior Angles 1 2 3 4 5 6 7 8 Alternate Interior Angles are always congruent!

4. · Inside the parallel lines ·On the same side of the transversal Examples: 3 & 5 4 & 6 Same-Side Interior Angles 1 2 3 4 5 6 7 8 Same-Side Interior Angles are always supplementary (add to 180 0 )

5. Corresponding Angles Li e on the same side of the transversal in corresponding positions Examples: 1 & 5 2 & 6 3 & 7 4 & 8 1 2 3 4 5 6 7 8 Corresponding Angles are always congruent.

6. 1 2 3 4 5 6 7 8 Alternate exterior angles ·lie on opposite sides of the transversal ·nonadjacent exterior angles

7. Examples: Find m<1 and m<2 75 0 1 2 t n m 1=75 0 2 =105 0

8. Examples: Find m<1 and m<2. 120 0 ab 2 1 q 1=120 2=60

9. Try this with your partner: Find m<3m<4m<5 m<6m<7m<8 a b c d 87 6 2 50 0 5 1 3 4 3=130 4=130 5=50 6=50 7=130 8=50

10. 80 0 70 0 1 2 Find m<1 and m<2. 2=70 1=100

11. (x+40) 0 x0x0 Find the value of the measured angles. x+40+x=180 2x+40=180 2x=140 x=70

12. Find the value of the labeled angles. (x+40) 0 (3x-10) 0 3x-10=x+40 2x=50 x=25

13. x0x0 y0y0 50 0 70 0 Find x and y. x=70 x+y+50=180 70+y+50=180 120+y=180 y=60