Degrees to Radians
Part of the Angles and the Unit Circle section of Coddy's Trigonometry journey. Lesson 15 of 57.
π radians and 180° are the same half turn. Divide both by 180: one degree is π/180 radians. So multiply an angle in degrees by π/180 to get radians.
Take 150°: 150×π/180. 150 and 180 share a factor of 30, so the fraction reduces to 5/6 and 150° is 5π/6 radians.
Leave radian answers as a fraction of π. That keeps them exact and shows the size at a glance: 5π/6 is five sixths of a half turn, just short of π.
Challenge
Turn 210° into radians. On the blank board, write x as the conversion, then a line with x exact, as a fraction of π in lowest terms. Then press Check.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Angles and the Unit Circle
1A Point on a Circle
Height on the CircleAcross: the CosineSame Height, Two AnglesRecap: Height and Across4Radians
What a Radian IsDegrees to RadiansRadians to DegreesRadians Without πTurns in RadiansRecap: Radians5Arc Length and Sector Area
Arc LengthArcs From DegreesFinding the AngleSector AreaRecap: A Slice of Pizza