1. Unit 2 - Right Triangles and Trigonometry
Chapter 8

2. Triangle Inequality Theorem
Need to know if a set of numbers can actually form a triangle before you classify it.
Triangle Inequality Theorem: The sum of any two sides must be larger than the third.
Example: 5, 6, 7
Since > > > 6 it is a triangle
Example: 1, 2, 3
Since 1+2 = > > 2 it is not a triangle!

3. Examples - Converse Can this form a triangle? Prove it: Show the work!

4. Pythagorean Theorem and Its Converse
𝑎 2 + 𝑏 2 = 𝑐 2 c a b
Converse of the Pythagorean Theorem
c2 < a2 + b2 then Acute
c2 = a2 + b2 then Right
c2 > a2 + b2 then Obtuse

5. Examples – What type of triangle am I?.
3. 4.

6. Pythagorean Triple
A set of nonzero whole numbers a, b, and c that satisfy the equation 𝑎 2 + 𝑏 2 = 𝑐 2
Common Triples
3, 4, 5
5, 12, 13
8, 15, 17
7, 24, 25
They can also be multiples of the common triples such as:
6, 8, 10
9, 12, 15
15, 20, 25
14, 28, 50

7. Special Right Triangles
Section 8.2
Special Right Triangles

8. Special Right Triangles
45°-45°-90°
x 𝑥 2 x
45°
90° x
𝑥 2

9. Examples – Solve for the Missing Sides
Solve or x and y
Solve for e and f

10. Special Right Triangles
30°-60°-90°
𝑥 x x
30°
60°
90° x
𝑥 3 2x

11. Examples – Solve for the Missing Sides
Solve for x and y
Solve for x and y

12. Right Triangle Trigonometry
Section 8.3
Right Triangle Trigonometry

13. Trigonometric Ratios Sine = Opposite Hypotenuse Cosine = Adjacent
Tangent = Opposite Adjacent
sin 𝑂 𝐻 cos 𝐴 𝐻 tan 𝑂 𝐴

14. SOHCAHTOA Remember this
SOHCAHTOA Remember this!!!! Write this on the top of your paper on all tests and homework!

15. Set up the problem
Sin
Cos
Tan

16. Set up the problem
Sin
Cos
Tan

17. Trigonometric Ratios:
When you have the angle you would use:
sin
cos
tan
When you need the angle you would use:
sin −1
cos −1
tan −1

18. Examples
Solve for the missing variable
Solve for the missing variable

19. Examples
Solve for the missing variable
Solve for the missing variable

20. Examples
Find m< A and m< B

21. Examples
Solve for the missing variables

22. Angle of Elevation and Angle of Depression
Section 8.4
Angle of Elevation and Angle of Depression

23. Elevation verse Depression – Point of View
Angle of Elevation
Angle of Depression

24. Examples – Point of View
Elevation
Depression

25. Examples – Point of View
Find the Angle Elevation
Find the Height of the boat from the sea floor.