SOLUTION: A cone of radius 3 cm and slant height 6cm is cut into four identical pieces. Calculate the total surface area of the four pieces. Any help would be appreciated!! maths exam to

Algebra ->  Surface-area -> SOLUTION: A cone of radius 3 cm and slant height 6cm is cut into four identical pieces. Calculate the total surface area of the four pieces. Any help would be appreciated!! maths exam to      Log On


   

Question 899858: A cone of radius 3 cm and slant height 6cm is cut into four identical pieces. Calculate the total surface area of the four pieces.
Any help would be appreciated!! maths exam to mmorow!!
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
sorry, in previous answer, I forgot to add inside area of each of the four pieces
let
SA=surface area of a cone
SA%5BI%5D=Inside surface area of each of 4 pieces of cone
total area:SA%2B4%2ASA%5BI%5D
first find SA
SA+=+pi%2Ar%5E2+%2B+pi%2Ar%2Al ................surface area
SA+=+3.14%2A3%5E2+%2B+3.14%2A3%2A6
SA+=+3.14%2A9+%2B+3.14%2A18
SA+=+28.26+%2B+56.52
SA+=+84.78
now find SA%5BI%5D
if cut in 4 peaces, you have 4 inside areas and each peace has SA%5BI%5D=2%2Ahr%2F2=hr
where heit h%5E2=l%5E2-r%5E2
h%5E2=6%5E2-3%5E2
h%5E2=36-9
h%5E2=27
h=sqrt%2827%29
h=5.2.............plug it in SA%5BI%5D=hr
SA%5BI%5D=5.2%2A3=15.6....inside area of one peace, and
so, 4%2ASA%5BI%5D=4%2A15.6=62.4
and SA%2B4%2ASA%5BI%5D=84.78%2B62.4=147.18 which rounded gives you SA%2B4%2ASA%5BI%5D=84.78%2B62.4=147cm%5E2