Unit 4  Objective 3  Values of Trigonometric Functions
Signs of trigonometric functions in all four Quadrants.
Reference Angles are always next to the xaxis
Given the reference angle , you can find the angle in the appropriate quadrant and given angle , you can find its reference angle.
1st Quadrant 
2nd Quadrant 
3rd Quadrant 
4th Quadrant 
The unit circle can be used to find trigonometric function for angles dividing the quadrants.
On the unit circle  x^2 + y^2 = 1 and  x = cos 
y = sin 
Examples: sin 90° = y = 1 cot 90° = 1/tan 90° = x/y = 0/1 = 0 
Special Triangles
Examples:

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