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.
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