Precalculus

1
Precalculus

• Radian Measure

2
The degree

• Common unit for measuring angles is the degree.
• ??? degrees in one revolution (or one circle).
  
• Origins in ancient Babylonia
• Another unit of measure in advanced
  mathematicsthe radian.

3
The radian

• When an arc of a circle has the same length as
  the radius of the circle, the measure of the
  central angle is, by definition, 1 radian.
• http//id.mind.net/zona/mmts/trigonometryRealms/r
  adianDemo1/RadianDemo1.html

4
You MUST know these!!!

• p 180 degrees
• 2p ___degrees
• Some things to remember
• Circumference of a circle C 2pr

5
Conversion Formulas
6
You try
7
You try
8
Radian Answers Should Be Exact (most of the time!)

• If it is appropriate to use decimals, your
  calculator can be used. You must set the MODE to
  the answer form (if your answer is to be in
  radians, your MODE must be in radians)
• Degrees written in decimal form will always have
  a degree symbol. Radians written in decimal form
  will not have any notation!

9
Ex 196 degrees ?? radians
10
1.35 radians ?? degrees
11
The Unit Circle