2. Radians are one unit for measuring angles. They have tremendous theoretical advantage in calculating and doing calculus with the trigonometric functions, but they have a major draw back. A straight angle and common fractions of a straight angle, like a right angle and the angles in regular polygons, have an irrational number of radians. A common alternative is to divide a straight angle into 180 degrees. The number of degrees is proportional to the number of radians. To change from radians to degrees, divide by pi and multiply by 180. So we will not specify which units we are using to measure angles. Instead of talking about the number of radians or degrees in an angle we will simply refer to its size.

Return to text