B D E What is the difference between a point and a vertex? Point D is listed as a vertex. Why? In order for point B and point E to become vertices (each as a single vertex), what would need to happen?

Acute Angle B Angle measure is greater than 0 degrees, but less than 90 degrees. D E B D E

Right Angle B Angle measure is exactly 90 degrees. D E B D E

Obtuse Angle B Angle measure is greater than 90 degrees, but less than 180 degrees. D E B D E

Straight Angle Angle measure is exactly 180 degrees. B E D B D E

Alternate Interior Angles Alternate Exterior Angles Use the following vocabulary words to show congruence between named angles. Alternate Interior Angles Alternate Exterior Angles Corresponding Angles Vertical Angles There are two pairs of Alternate Interior Angles. Name them below: _________________________ and __________________________ There are two pairs of Alternate Exterior Angles. Name them below: _________________________ and __________________________ There are four pairs of Corresponding Angles. Name them below: _________________________ and __________________________ There are four pairs of Vertical Angles. Name them below: _________________________ and __________________________

obtuse right acute

Name each triangle (using 3 letters). What type of triangle is it based on its angles? Are any of the triangles congruent?

Turn to Page S.68 B D E Angles ABC, ____ , ____.

Turn to Page S.69

110 28 Turn to Page S.70 Informal argument: I know that ALL triangles must add up to 180 degrees. I know my angles of 28, 42 and 110 are true because their sum is 180 degrees, forming Triangle CDE. 110 28

Which angle measures 83 degrees? Turn to page S.71 Which angle measures 83 degrees? Which angle measures 64 degrees? What is the measure of Angle ACB? How do you know? Which angle measures 40 degrees? Which angle measures 101 degrees? What is the measure of Angle DFE? How do you know?

If all angles have a measure of x degrees, what does that mean? Turn to page S.72 If all angles have a measure of x degrees, what does that mean? A triangle with all sides and angles measuring the same is called an _________________________ ?

1 2 What do you know about the triangle? What angle relationships do you see? 1 2