Answer:
417.4ft^2
Step-by-step explanation:
Surface area of a cone = πr(r+√r²+h²)
r is the radius
h is the height
Substitute
Surface area of a cone = π(5)(5+√5²+21²)
Surface area of a cone = πr(5+√25+441)
Surface area of a cone = π(5)(5+21.59)
Surface area of a cone = 3.14*5*26.59
Surface area of a cone = 417.4ft^2
Hence the surface area of the cone is 417.4ft^2
