1. RADIAN THE UNIT CIRCLE

2. REMEMBER Find the circumference of a circle that has a radius of 1. C = 2πr C = 2π(1) C = 2π

3. RADIANS We can talk about a circle according to it’s central angle: 90° We can talk about a circle according to how much of the circumference the angle involves … OR

4. CONVERSION How many degrees are in one complete circle? 360° Using π, how much of the circumference is covered in one complete turn? = 2π Which simplifies to

5. TRY … 1. Convert 30° to radians: 2. Convert to degrees: 1 6 1 1 1 90°