1.  Triangle Song - YouTube Triangle Song - YouTube

3. Triangles  A triangle is a 3- sided polygon. Every triangle has three sides and three angles. When added together, the three angles equal 180°.

4. Acute Triangles  An acute has three angles that are less than 90°.  Remember AAAA.  ALL ANGLES ARE ACUTE!

5. Obtuse Triangles  An obtuse triangle is a triangle in which one of the angles is greater than 90° and the other two angles are acute.  One obtuse angle and Two acute angles

6. Right Triangles  A right triangle is triangle with an angle of 90°.  One right angle and two acute angles

7. Scalene Triangles  A triangle with three unequal sides.  The “mean scalene” doesn’t want to get along. All of the sides are different lengths!

8. Isosceles Triangles  To remember this triangle….. “eye” …soceles” It will remind me that I have 2 eyes. The “e-l-e-s” at the end is close to how we spell the word eyes.  An isosceles triangle has 2 sides that are the same (equal in length).  It has at least 2 acute angles. An isosceles triangle is a triangle with two equal sides. When two sides are the same we call them CONGRUENT.

9. Equilateral Triangles  An equilateral triangle is a triangle with all three sides of equal length  All the angles will be the same size (acute).  Equilateral you are so fine, all your sides are the same size!

10. Triangle Quiz  Please complete the following quiz that covers the information that was just presented to you.

11. Question 1  If a triangle has three unequal sides it is a ______ triangle. A) Scalene B) Obtuse C) Isosceles  Answer: A) Scalene

12. Question 2  A triangle which has three equal sides is a ______ triangle. A) Acute B) Equilateral C)Scalene  Answer: C) Equilateral

13. Question 3  A triangle with (at least) two equal sides is a ______ triangle. A) Scalene B) Isosceles C) Congruent  Answer: B) Isosceles

14. Question 4  Two triangles that are equal are called ______ triangles A) Acute B) Obtuse C) Congruent  Answer: C) Congruent

15. Question 5  A triangle with all three sides of equal length is a ______ triangle. A) Equilateral B) Right C) Equiangular  Answer: A) Equilateral

16. Question 6  A triangle with an angle of 90° is a ______ triangle. A) Acute B) Right C) Congruent  Answer: B) Right

17. Question 7  A triangle in which all three angles are less than 90° is a ______ triangle. A) Right B) Acute C) Scalene  Answer: B) Acute

18. Question 8  A triangle in which one of the angles is greater than 90° is a ______ triangle. A) Obtuse B) Isosceles C) Acute  Answer: A) Obtuse

19.  http://www.aaamath.com/geo318- triangle-angles.html http://www.aaamath.com/geo318- triangle-angles.html