Parallel and Perpendicular Lines

Objective Learn to recognize parallel and perpendicular lines.

Parallel and Perpendicular Lines…A plane is an infinite, flat surface. Lines in a plane that never meet are called Parallel Lines.

Perpendicular Lines: are lines that intersect to form 90 degree angles. For Example:

Lines that intersect 2 or more parallel lines diagonally are called transversal. When a transversal line intersects 2 parallel lines, pairs of congruent angles (angles with the same measures) are formed. Here are some examples…

Vertical Angles: <2 and <3; <1 and <4; <6 and <7; <5 and <8.

Alternate Interior Angles: < 4 and <5; <3 and <6

Corresponding Angles:

< 1 and <5; <3 and <7 <2 and <6; <4 and <8

Examples: Determine if each pair of lines is parallel, perpendicular, transversal, or neither.

1) 2)

answer: __________ answer:_________ 3)

Answer: ___________________

Homework: In 1-8, write the word that best describes the lines. (Parallel or Perpendicular)

1. The strings on a guitar. _______________

2. Sidewalks on opposite sides of the street. ________________

3. The lines that make up a plus + sign. ___________________

4. The hands of the clock at 9pm. _____________________

5. Two palm trees in Los Angeles. _____________________

6. The window panes in the classroom. _________________

7. Ask an adult and name 2 parallel streets. __________________

8. Ask an adult and name of 2 perpendicular streets. _________________

9. Look at the picture. Name 2 congruent (same) angles. ________________

10. Look at the picture and name 2 parallel lines. _____________________