1. 4.1 Angles Formed by Intersecting Lines
Essential Question: How can you find the measures of angles formed by intersecting lines?

2. Vertical Angles- the angles that are opposite each other when two lines intersect

3. Find

4. The measures of two vertical angles are 58° and (3x+4)°
The measures of two vertical angles are 58° and (3x+4)°. Find the value of x.
The measures of two vertical angles are given by the expressions (x+3)° and (2x-7)°. Find the value of x. What is the measure of each angle?

5. Complementary Angles- two angles whose measures have a sum of 90°
Supplementary Angles- two angles whose measures have a sum of 180°

6. 1. 2.

7. Flow Proof- a proof that uses boxes and arrows to show the structure of the proof.

8. Two-column proof- numbered statements and reasons that show the logical order of an argument

9. Paragraph proof- when a proof is written in paragraph form
You are given that PQ=XY. By the definition of congruent segments, PQ=XY. By the symmetric property of equality, XY=PQ. Therefore, by the definition of congruent segments, it follows that XY=PQ.

10. Tear out pages
Do problems 1-5, 10-12