what is the surface area of a cone with a diameter of 1.8 and a slant height of 4

Question

The base of a cone has a diameter of 1.8 inches and a slant height of 4 inches. what is the surface area of this cone?

Answer 1

Surfacearea of cone (SA) = ∏rs+∏r^2

r = radius

s = slant height

d = 1.8"

d = 2r

r = 1.8/2 = 0.9"

s = 4"

SA = (3.14)(0.9)(4)+(3.14)(0.9)^2

= 11.304+2.5434

= 13.8474 Squre inches.