## Tuesday, 16 April 2013

### 16/4 MATH SCRIBE POST – Justin

~(•O•)~ E Math: Trigonometry Revision

CONTENT:
1. Trigonometric Functions
2. Trigonometric Rules
3. Special Angles!

*Do note that most, if not all, of these rules apply to only right angled triangles unless stated otherwise.

1. Trigonometric Functions
Toa (Big) – T for tangent, and O is before A.
Therefore: tan(x) = O/A
Cah (Leg) – C for cosine, and A is before H
Therefore: cos(x) = A/H
Soh (Lady/Auntie) – S for sine, and O is before H.
Therefore: sin(x) = O/H

sin^2(x) = (sin(x))^2  <–– THIS RULE applies to all trigonometric functions

2. Trigonometric Rules
1. tan(x) = sin(x) ÷ cos(x)

2. sin(90 - x) = cos(x)
cos(90 - x) = sin(x)
tan(90 - x) = 1/(tan(x))

3. sin^2(x) + cos^2(x) = 1

4. sin(180 - x) = sin(x)
cos(180 - x) = -cos(x)
tan(180 - x) = -tan(x)

5. PYTHAGORAS THEOREM
a^2 + b^2 = c^2

6. Using the Z-rule
angle of depression = angle of elevation

3. Special Angles
Here is a table for your viewing pleasure:

On another note you could use two triangles,
1. Sides 1, 2, √3.
2. Isosceles Triangle of 1, 2, and √2.