Why do we need a protractor in measuring traffic cone?
It’s like answer 1 said, except the ratio of the slant height to the radius of the bottom is 1/cosine, not the tangent, of the angle between the bottom of the cone and its side. It is also equal to 1/sine of half the angle of the cone at its apex. So the easiest way to do this is to divide the radius by the slant height, find the angle whose sine equals the result, and double that to get the cone angle.
