Arc length from radians

To find the length of an arc (of a sector), we can just calculate:

r\theta

Where:

• r is the radius of the sector(’s circle)
• \theta is the angle of the sector

Equation

The full equation would be:

l=r\theta

where:

• l is the length of the arc
• r is the radius of the circle
• \theta is the angle of the sector

Rearranging to find the arc length

l=r\theta

Rearranging to find the radius

r=\frac l{\theta}

Rearranging to find the angle of the sector

\theta=\frac lr