### Home > PC > Chapter 4 > Lesson 4.1.4 > Problem4-54

4-54.

Roger is in an Algebra 2 class and has found the radian setting on his calculator. He has not learned about radians but would like to know.

1. Explain to Roger how a radian is defined.

1 radian is the angle measure found by wrapping one radius around a circle.
$\frac{\pi\text{ radians}}{180\degree}$

2. Show him how to change 240° to radians.

Use a Giant One of $240\degree\cdot\frac{\pi\text{ radians}}{180\degree}$.

3. Show him how to change $\frac { 5 \pi } { 6 }$ radians to degrees.

$\frac{5\pi}{6}\cdot \frac{180\degree}{\pi}=?$