Radian and Degree Measure

Radian Measure A radian is the measure of a central angle that intercepts an arc length equal to the radius of the circle Radians measure the amount of rotation from the initial side to the terminal side of an angle

Converting degrees to radians Multiply the degree by DO NOT type the π into the calculator! Type in the fraction and use MATH 1: Frac to reduce. Your answer must have a pi symbol! Examples: Convert to radians –38° –-224° –126°

Converting radians to degrees Multiply by The pi symbols should cancel out. You do NOT have to type the pi symbol into your calculator since it will cancel. Remember to put a degree symbol in your answer! Examples: Convert to degrees

Radians without π Any angle measure WITHOUT a degree symbol is in radian measure!! Convert 2 radians to degrees This is the only time you should type the pi symbol into your calculator! 2(180/π) The pi symbol is under 2 nd ^

Complementary angles Angles whose sum is 90ß or Ä /2 Angles larger than 90 ß (1.57 radians) do NOT have a complement Example: Find the complement of each angle: a.) 62b.) Ä /5c.) 2 radians

Supplementary angles Angles whose sum is 180ß Examples: Find the supplement of each angle a.) 112ßb.) 31ß c.) 31Ä/36

Coterminal Angles Standard position- vertex at the origin and the terminal side rotates to form an angle All angles can be measured in a clockwise AND counter-clockwise direction

Finding coterminal angles In degrees, add and/or subtract 360 In radians, add and/or subtract 2Ä (remember do NOT put the Ä symbol into your calculator) Examples: Find one positive and one negative coterminal angle a.) 116ß b) 5Ä/11