What is the formula for calculating the central angle of a cone?

[ivan77]

Hi,

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

Thanks,

Ivan77

 

[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.