How do I find the slant height of a cone with only the given surface area and radius?

Question

The surface area of a cone is 55pi cm squared. The radius is 5 cm. What is the slant height?

Answer 1

SA = r*s*pi + r²*pi

55pi = 5*s*pi + (5)²pi

55pi = 5*s*pi + 25*pi

30pi = 5s*pi (subtracted 25pi from both sides)

s = 6 cm (divide both sides by 5pi, isolating s)

Solution: Slant height is 6 cm