The document provides an overview of trigonometric ratios and their applications. It defines sine, cosine, and tangent ratios for right triangles. Examples are given to find specific trigonometric ratios. Mnemonics are introduced to remember the trig functions. Applications like finding angles of elevation/depression are demonstrated. Students are assigned homework from their textbooks and informed of an upcoming test.

1. Geom9­9and9­10.notebook February 21, 2012
BELL WORK: Find the following ratios:
a) OW to WP
b) OP to WP
c) VR to RA
d) VA to RA
What do you notice?
P A
60o 60o
4
10
O W V R
Today, we will cover the end of chapter 9. The things you learn
today will follow you throughout high school and even to college.
Look back at your bell work. We found some ratios of right
triangles. The ratios of right triangles are consistent.
Engineers, scientists, mathematicians, and everyone cool
thought it would be useful to give these ratios names.
1

2. Geom9­9and9­10.notebook February 21, 2012
Sine:
B
c
Cosine: a
C b A
Tangent:
Example: Find each
ratio. C
15
a. sin A 8
b. cos A B
A 17
c. tan A
d. sin B
e. cos B
f. tan B
2

3. Geom9­9and9­10.notebook February 21, 2012
Mnemonics that I have learned:
SOH CAH TOA
Some Old Hippie
Caught Another Hippie
Tripping On Acid.
Sin, cos, and tan can be very useful in finding lengths and angles
in real life. In order to do this, we need to know a couple of terms:
angle of elevation ­ If you are looking upward at a point, this is
how the angle is described.
angle of depression ­ If you are looking downward at a point, this
is how the angle is described.
You will use the Table of Trigonometric Ratios as a reference to
solve some of these types of problems.
3

4. Geom9­9and9­10.notebook February 21, 2012
Example: a) Find m D to the nearest degree.
b) Find e to the nearest tenth.
E
f = 20.1
d = 11.2
F e D
To an observer on a cliff 360m above sea level, the angle of
depression of a ship is 28 degrees. What is the horizontal distance
between the ship and the observer?
4

5. Geom9­9and9­10.notebook February 21, 2012
EXIT SLIP: Find each of the following in the
Table of Trigonometric Ratios.
a) sin 21
b) tan 52
c) cos 5
Homework: p.420 #3­10,15
p.425 #2­7,15
Due Thursday
Test Friday over chapter 9
binder check Friday
5