# ATL (Criteria B): Exploring Radians and Degrees

- Author:
- siujiawong, HaileyMF

- Topic:
- Angles

## Slowly move the "Change Angle" slider all the way to the right until the entire circumference has been traced.

1) How many different colors arc lengths are formed?

## 2) One arc represents one radian.

You may drag the radius slider to change the length of the radius. What did you observe about the length of one arc and the length of the radius?

The length of one arc ______ to the length of the radius.

## Now, make sure the diagram is a unit circle, i.e. r = 1.

3) How many radians are in a circle? (HINT: How many arcs is formed for a circle.)

## Next, determine the degrees formed by one arc length (which is 1 radian).

## 4) How many degrees are in 1 radian?

[Hint: supposed to be an acute angle.]

## 5) Combine Q2 & Q4.

You mentioned that there are __x radians__ in a circle (in Q2) and

__1 radian=__in Q4. What can you conclude from these two pieces of information?

**degrees***y*## 6) Suggest next pattern.

Suggest **how** I should calculate the length of 2 colored arcs of a circle with a radius of 3.0.
[Reminder: *Explain the process* instead of the final answer.]

## 7) Suggest a general rule.

Suggest how I should calculate the length of an arc of a circle, * s* with a radius of

**where the arc formed an angle of radian. Write a formula relate**

*r***, .**

*s, r*