Quadrants

Finding Reference angle by Quadrant

• Quadrant 1 - itself

• Quadrant 2 - 180 Degrees minus the angle

• Quadrant 3 - The angle minus 180 degrees

• Quadrant 4 - 360 minus the angle

Finding Reference Angles

• The blue portion of graph is the original angle

• The red portion is reference angle

  
  

Coterminal Angles

On slide 6, angles 500° and 140° are coterminal because their terminal sides coincide. An angle coterminal with a given angle can be found by adding or subtracting multiples of 360°.

Ex: Find one Positive and one Negative Angle that are coterminal with -45° and 395°

​There are many such angles, depending on what multiple of 360° is added or subtracted.