Given that the generatrix length of the cone is 30, and the center angle of the fan-shaped circle is 120 ° after the side expansion, the bottom radius of the cone is 0______ Detailed explanation

Given that the generatrix length of the cone is 30, and the center angle of the fan-shaped circle is 120 ° after the side expansion, the bottom radius of the cone is 0______ Detailed explanation

Perimeter: 30x120 / 360x