1. Chapter 13 Section 3
Radian Measure

2. Central Angle
Central Angle = Intercepted Arc
(1,0)
1 unit

3. 1 Radian
Central Angle when the Radius = Arc Length
1 radian
(1,0)

4. To convert Degrees to Radians or Radians to Degrees

5. To convert 1200 to Radians or Radians to Degrees

6. To convert 1200 to Radians or Radians to Degrees

7. Unit Circle
For angles in standard position we use the variable q to show we are talking about an angle ( q
(1,0)
1 unit

8. For any point on the unit circle, we can find the coordinates by using the angle in standard position and the rule
(cos(q) , sin(q))
(cos(300) , sin(300))
300
(1,0)
1 unit

9. Cosine and Sine of 30-60-90 triangles2 1

10. Cosine and Sine of 30-60-90 triangles2 1
300

11. Cosine and Sine of 45-45-90 triangles1
450 1

12. Make a 30-60-90 triangle and look at the coordinates
For angles with a terminal side not in the 1st quadrant
Make a triangle and look at the coordinates
(- , )
1200
(1,0)
1 unit

13. Make a 30-60-90 triangle and look at the coordinates
For angles with a terminal side not in the 1st quadrant use the rule QI (+,+) QII (-,+) QIII (-,-) QIV(+,-)
Make a triangle and look at the coordinates
2100
(1,0)
1 unit
(- ,- )

14. For angles with a terminal side not in the 1st quadrant use the rule QI (+,+) QII (-,+) QIII (-,-) QIV(+,-)
U Try
3000
(1,0)
1 unit
( ,- )

16. Do Now
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