System of Measurement of Angles

Sexagesimal System

$1$ right angle $= 90^o$

$1^o = 60$ minutes $= 60'$

$1' = 60$ seconds $= 60''$

Centesimal System

$1$ right angle $= 100$ grads  $= 100^g$

$1$ grade $= 100$ minutes $= 100'$

$1$ minute $= 100$ seconds $= 100''$

Circular System

Radian: One radian $(1^c)$, is the measure of the angle subtended at the center of a circle by an arc of length equal to the radius of the circle.

$1^c =$ $\frac{angle}{\pi}$

The number of radians in an angle subtended by an arc of a circle is equal to $\frac{arc}{radius}$

$1^c =$ $\frac{180^o}{\pi}$