1. Unit 4A – Geometric Figures Lesson 3 Triangles
Unit 4 Geometry
Unit 4A – Geometric Figures
Lesson 3
Triangles

2. Lesson 3: Triangles
Objective: Swbat classify triangles. Do Now: Quick Check

3. Lesson 3: Triangles
Definitions Triangle has three sides and three angles. Congruent segments are sides with the same length. Acute triangle has all acute angles. Right triangle has one right angle. Obtuse triangle has one obtuse angle. Scalene triangle has no congruent sides. Isosceles triangle has two congruent sides. Equilateral triangle has three congruent sides.

4. Lesson 3: Triangles
Angles of a Triangle Rule The sum of the measures of a the angles of a triangle is 180°. <1 + <2 + <3 = 180° 1 2 3

5. Lesson 3: Triangles
Sides of a Triangle Rule The lengths of the two shorter sides must be greater than the longer side > 9 Could the sides of a triangle be 3, 6 and 10 inches?
6 in
4 in
9 in

6. Lesson 3: Triangles
Find the missing angle measure. Then classify by its sides and angles.
43°
65° x°

7. Lesson 3: Triangles
Find the missing angle measure. Then classify by its sides and angles.
130° x° x°

8. Lesson 3: Triangles
Find the missing angle measure. Then classify by its sides and angles. x°
45°

9. Lesson 3: Triangles
Find the missing angle measure. Then classify by its sides and angles. x° x° x°

10. Classwork Guided Practice #1 – 4 Independent Practice #1 – 8
Problem Solving Practice #1 - 6

11. Closure Question: What is the sum of the angles in a triangle?
Exit Ticket
Homework: Practice #1 - 16

12. Exit Ticket
In Triangle ABC, Angle A is 65°, Angle B is 50°, then what is the measure of Angle C?

13. Homework