1. Do Now Write homework in your agenda
Take out Triangle Angles HW from yesterday
Prepare to ask questions

2. Parallel Lines & Transversals Intro

3. Vocabulary Review

4. A right angle measures 90°.
A right angle can be labeled with a small box at the vertex.
Reading Math

5. Acute Angles – measure less than 90 degrees.
Obtuse Angles – measure more than 90 degrees.

6. 1st & 2nd Tabs in
Vocab Flip Book

7. Complementary angles: Angles whose measures sum to 90°
Complementary angles: Angles whose measures sum to 90°. A right angle measures 90°.
Angle symbol ∡
Supplementary angles: Angles whose measures sum to 180°. A straight line measures 180°.

8. 3rd Tab in Vocab Flip Book

9. Vertical Angles: Angles formed by 2 intersecting lines
Vertical Angles: Angles formed by 2 intersecting lines. Vertical angles are always congruent.
Congruent Symbol: ≅
In the figure, 1 and 3 are vertical angles, and 2 and 4 are vertical angles.

10. Example: Finding the Measure of Vertical Angles
In the figure, 1 and 3 are vertical angles, and 2 and 4 are vertical angles.
If m1 = 37°, find m 3.
1 and 3 are vertical angles.
m3 = 37°

11. 4th Tab in Vocab Flip Book

12. Parallel lines are lines in a plane that never meet, like a set of perfectly straight, infinite train tracks.
The symbol for parallel is ||.

13. The railroad ties are transversals to the tracks.
The tracks are parallel.
A transversal is a line that intersects 2 or more lines in the same plane.
It creates angles with special properties when it intersects parallel lines.

14. Example: Identifying Congruent Angles Formed by a Transversal
Look at the angles formed by the transversal and parallel lines. Which angles seem to be congruent?
1, 3, 5, and 7 all measure 150°.
 2, 4, 6, and 8 all measure 30°.

15. Example Continued
Angles marked in blue appear to be congruent to each other, and angles marked in red appear to be congruent to each other. 7 2 1 3 4 8 6 5 7 8

16. 5th Tab in Vocab Flip Book

17. Perpendicular lines: Lines that intersect at 90° angles.
The symbol for perpendicular is .
Coincidental Lines are the same line.

18. 6th Tab in Vocab Flip Book

19. Alternate interior angles: 2 angles
on opposite sides of the transversal and inside the parallel lines. These angles are ≌.
The pair of blue and the pair of pink angles are alternate interior angles.

20. 7th Tab in Vocab Flip Book

21. Alternate exterior angles: 2 angles
on opposite sides of the transversal and outside the parallel lines. These angles are ≌.
The pair of blue and the pair of pink angles are alternate exterior angles.

22. 8th Tab in Vocab Flip Book

23. Corresponding angles: Angles in matching corners when 2 parallel lines are crossed by a transversal. Corresponding angles are ≌.
The pair of pink angles are corresponding. The pair of purple angles are corresponding. The blue pairs and green pairs are also corresponding.

24. Other Angles

25. Same side interior or consecutive interior angles are 2 angles inside the 2 parallel lines along the same side of a transversal line. These angles are supplementary. 1 2 3 4 5 6 7 8
Ex: <3 and <5 are same side interior angles.
<4 and <6 are same side interior angles.

26. Same side exterior or consecutive exterior angles are 2 angles outside the 2 parallel lines along the same side of a transversal line. These angles are supplementary. 1 2 3 4 5 6 7 8
Ex: <1 and <7 are same side exterior angles.
<2 and <8 are same side exterior angles.

27. Example: Finding Angle Measures of Parallel Lines Cut by Transversals
In the figure, line l (L) || line m. Find the measure of the angle
4.
All obtuse angles in the figure are congruent.
m4 = 124°