1. Degrees and radians
Unit 4.2

2. Practice
Find the measure of each angle

3. Practice
Convert from Degrees to Radians or Radians to Degrees

4. Arc Length
𝑠=𝑟𝜃

5. Find the arc length of the intercepted arc in each circle with the given central angle measure and radius. Round to the nearest tenth.
𝜋 4 , 𝑟=5 𝑐𝑚
60°, 𝑟=2𝑖𝑛
2𝜋 3 , 𝑟=2𝑚
135°, r=0.5 ft

6. Linear and Angular Speed
Recall that the formula for velocity is:
If we want to know angular velocity, then the formula would be:
𝜔= 𝜃 𝑡
Where 𝜃 is the angular distance covered.

7. Real World Example A bicycle messenger rides the bicycle shown.
During one delivery, the tires rotate at a rate of 140 revolutions per minute. Find the angular speed of the tire in radians per minute.
On part of the trip to the next delivery, the tire turns at a constant rate of 2.5 revolutions per second. Find the linear speed of the tire in miles per hour.

8. HW:
Quiz Next Class (4.1 &4.2)
Finish Practice Sheets
KNOW THE CIRCLE!