# Central angle of a cone?

1. Aug 12, 2010

### ivan77

Hi,

If you have a cone (right angle) with radius r, slant lenght l, how is the central angle theta = 2*pi*r/l?

Thanks,

Ivan77

2. Aug 12, 2010

### ivan77

Realized the problem. It boils down to the formula for a arclength s = theta*radius (circle) where s is 2*pi*r (r is the radius of the cone) and the l is the radius of the circle.