Degrees to radians: 1° = π/180 radians

1^{\circ} = \dfrac{\pi}{180}\text{ rad}\qquad 1\text{ rad} = \dfrac{180}{\pi}^{\!\!\circ}

One degree is π/180 radians, and one radian is 180/π degrees - so multiply by π/180 going into radians and by 180/π coming out. Radians are the unit calculus assumes, which is why arc length, sector area and every derivative of a trig function require them. Getting caught in degree mode is the single most common source of wrong answers on a calculator.

unit conversion

Related Basics identities

SOHCAHTOA Arc length Sector area

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