6.4 Radians, Arc Length, and Angular Speed

  • Find points on the unit circle determined by real numbers.

  • Convert between radian measure and degree measure; find coterminal, complementary, and supplementary angles.

  • Find the length of an arc of a circle; find the measure of a central angle of a circle.

  • Convert between linear speed and angular speed.

Another useful unit of angle measure is called a radian. To introduce radian measure, we use a circle centered at the origin with a radius of length 1. Such a circle is called a unit circle. Its equation is x2+y2=1.

Distances on the Unit Circle

The circumference ...

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