Week 2 The unit Circle

Week 2

Angle	Sin	Cos	Tan=Sin/Cos
30°			1/√3 = √3/3
45°			1
60°			√3

How To Remember?

To help you remember, think "1,2,3" :

• sin(30°) = ^√1/₂ = ¹/₂ (because √1 = 1)
• sin(45°) = ^√2/₂
• sin(60°) = ^√3/₂

And cos goes "3,2,1"

• cos(30°) = ^√3/₂
• cos(45°) = ^√2/₂
• cos(60°) = ^√1/₂ = ¹/₂ (because √1 = 1)

Soh Cah Toa

 Cosine is equal to the x coordinate where this radius intersects the Unit circle

The Sine is equal to the y coordinate where the coordinate  intersects the unit circle

y

Now, in this same circle, let us draw a right triangle 

θ

θ rad.

P = (x, y)

•

y

x

1

Using the right triangle definitions of the trigonometric functions

we can write

sin θ =

opposite

hypotenuse

= y,

and

cos θ =

adjacent

hypotenuse

= x.

This week I was a little puzzled with what my teacher threw at me..... "THE UNIT CIRCLE"
The unit circle is a tricky concept to grasp but with Khan Academy's continuous assistance I am understanding the Unit Circle better and better each day