Radian Measure of a

Circleanother way to measure

angles!

Opener:• What is the

circumference of a tire with a radius of 18”?

• How many complete revolutions does the tire make over 1000 feet?

18"

What is a radian????

Where does come from??(It’s not the oven)

• We know that • This tells us that every circle’s

circumference has radii’s of distance, or that the ratio of a circle’s circumference to its radius is always !!!!

How to convert from …

• Degrees to Radians: • Radians to Degrees:

180multiply by

180multiply by

Convert 235 degrees to radians:

235°{————}= radians

Convert radians to degrees:

=

State your answer in terms of π!

If you walk around a circular track with a radius of 100m atotal of eight times, how many radians will you have traveled?

What if the radius of the track were 1000m instead of 100m?

This is why we don’t state distances in terms of radians!!!

Radians are measures of angles and arcs and are used in lieu of degrees.

We often see fractional portions of π referring to angles. What do the following radian measures refer to in terms of degrees?

Tonight’s

Homework