Unformatted text preview: ◦ cuts off an arc of length 2 π r , which is the same as the circumference of the circle. So associating the central angle with its intercepted arc, we could say, for example, that 360 ◦ “equals” 2 π r (or 2 π ‘radiuses’). The radius r was arbitrary, but the 2 π in front of it stays the same. So instead of using the awkward “radiuses” or “radii”, we use the term radians : 360 ◦ = 2 π radians (4.1) The above relation gives us any easy way to convert between degrees and radians: Degrees to radians: x degrees = p π 180 · x P radians (4.2) Radians to degrees: x radians = ± 180 π · x ² degrees (4.3) 87...
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 Fall '11
 Dr.Cheun
 Calculus, Angles, Measuring Angles, Radian, central angle

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