1. Standard:9 geometry triangles

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

3. Acute Triangles
A triangle in which all three angles are less than 90°.

4. Obtuse Triangles
An obtuse triangle is a triangle in which one of the angles is greater than 90°.

5. Right Triangles
A right triangle is triangle with an angle of 90°.

6. Scalene Triangles
A triangle with three unequal sides.

7. Isosceles Triangles
An isosceles triangle is a triangle with (at least) two equal sides.

8. Isosceles Triangle Theorem
The following movie shows that if two sides of a triangle are congruent, then the angles opposite those sides are congruent.

9. Equilateral Triangles
An equilateral triangle is a triangle with all three sides of equal length.

10. Equiangular Triangles
An equiangular triangle is a triangle which has three equal angles.

11. Congruent Triangles
Congruent triangles are triangles whose corresponding angles and sides are congruent. 
They are exactly the same size and shape.

12. The Hypotenuse
The hypotenuse of a right triangle is the triangle's longest side, i.e., the side opposite the right angle.

13. The Pythagorean Theorem
For a right triangle with legs a and b and hypotenuse c, a2+b2=c2.

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

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

16. Question 2
A triangle which has three equal angles is a ______ triangle.
A) Acute
B) Equilateral
C) Equiangular
Answer:
C) Equiangular

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

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

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

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

21. 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

22. 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

23. Question 9 What is the Hypotenuse of a right triangle? Answer:
A) The smallest angle.
B) The side opposite the right angle.
C) The right angle.
Answer:
B) The side opposite the right angle.

24. Question 10 The Pythagorean Theorem states … Answer: C) a2+b2=c2
A) pr2
B) (a+b)2/2=c
C) a2+b2=c2
Answer:
C) a2+b2=c2

25. Question 11 Use the Pythagorean Theorem to solve the following:
b = 12
c = ?
Answer:
c = 13