The length of the cone is 18 cm. The difference between the curved surface area of the cone and the total surface area of the cone is 616 cm². If the side of the equilateral triangle is 4 cm more than the radius of the cone, then find the perimeter of the equilateral triangle.
1
72 cm
2
64 cm
3
78 cm
4
54 cm
5
60 cm