The base circumference of fruit cone is 20 π, and the center angle of the fan-shaped circle is 120 ° after the lateral expansion

The base circumference of fruit cone is 20 π, and the center angle of the fan-shaped circle is 120 ° after the lateral expansion

The radius of the circle where the sector is located is r, and the generatrix length of the cone is r
2πR:360°=20π:120°
R=360°*10/120°=30.