Question

What is the surface area of a cone with a radius of 3 cm and a length of 8 cm

Answer 1

Answer: surface area = 108.8 sq. cm

Step-by-step explanation:

A=πr(r+√h2+r2)

Answer 2

Answer:

108.8cm^2

Step-by-step explanation:

Surface Area

A = πr(r+ √h2+r2)

A= π3 * (3 +1/3)  √64 + 9  (+ 3) = sqroot 17 +3 = 20 + (3 x 4) = π32

A= 108.7

Volume

V=πr2h/3

V= π9*8 = π72/3 = 226.28/3

V= 72.4cm^3

Additional

The cone has a radius of 3cm and height of 8cm, find total surface area of the cone.

To begin with we need to find slant height of the cone, which is determined by using Pythagoras, since the cross section is a right triangle.

l2 = h2 + r2

l2 = 64 + 9

l = √(73)

l = 8.54 cm

And the total surface area of the cone is:

SA = πr2 + πrl

SA = π · r · (r + l)

SA = π · 3 · (3 + 8.54)

SA = π x 3 . 11.54

SA = 9.42477796077 x 11.54 = 108.76 cm2

SA = 108.8cm^2