1. Radian Angle Measures 1 radian = the angle needed for 1 radius of arc length on the circle still measures the amount of rotation from the initial side to the terminal side. Radians often use  to symbolize the angle measure.  C = 2  r - Distance around a circle is circumference. C = 2  r -Radians uses the unit circle, so r = 1. This makes the distance 2  around the circle 2 .

2. III IIIIV Quadrants remain the same, but quadrant angles are now in radians. In what quadrant would the terminal side of each of the following angles lie? 11  6 -7  4 2  3 -20  3

3. Finding Coterminal Angles in Radians In degrees: Add or subtract any multiple of 360 o. In radians: Add or subtract any multiple of 2 . *Be careful when adding fractions* Easiest Way: Add the numbers on calculator without the  then insert the  in the final answer.

4. Examples: Find one positive and one negative coterminal angle to.

5. Reference Angle with Radians an acute angle formed by the terminal side of any angle (  ) and the x-axis (  should be a positive angle 0 – 2  )   Quadrant I  =  Quadrant II  Quadrant III  =  Quadrant IV 

6. Find the reference angle (  ) of each given angle (  1) 2  /3 2)7  /6 3)11  /3 4)-4  /3 5)-13  /5

7. I HATE Fractions!