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}

Relation between Degrees and Radians

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