In the past, you have used degrees to measure angles. When angles are used in periodic functions, they are often measured in larger units called radians.Remove the cylinder and string. Use paper folding to locate the center of the circle. (Fold the circle onto itself and crease the paper along a diameter. Repeat to get a second diameter.) Draw a central angle that intercepts one radius unit of arc. The measure of the angle you drew in Question 4 is 1 radian.