Answer:
surface area of a cone = 132.935πft
Explanation:
to find the surface area of a cone
given that
radius = 5ft
height of cone = 21ft
recall that the formulae for finding the surface area of a cone = πr( r + √ h² + r²)
so,
surface area of a cone = πr( r + √ h² + r²)
surface area of a cone = π x 5( 5 + √ 21² + 5²)
surface area of a cone = 5π ( 5 + √ 441 + 25)
surface area of a cone = 5π( 5 + 21.587)
surface area of a cone = 5π (26.587)
surface area of a cone = 132.935πft