Find the surface area of a cone with radius 5 ft and height 21 ft substitute pi for 3.14​

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

c.35

step-by-step explanation:

8+13=21

21+8=29

29+6=35