SOLUTION: A pencil consisting of 3 parts - a cone, a cylinder and a hemisphere. Given the radius of the hemisphere is 0.7cm and the slant height of the cone is 2 times its radius. Find the t

Algebra ->  Surface-area -> SOLUTION: A pencil consisting of 3 parts - a cone, a cylinder and a hemisphere. Given the radius of the hemisphere is 0.7cm and the slant height of the cone is 2 times its radius. Find the t      Log On


   

Question 708294: A pencil consisting of 3 parts - a cone, a cylinder and a hemisphere. Given the radius of the hemisphere is 0.7cm and the slant height of the cone is 2 times its radius. Find the total surface area of the pencil. (Answer given in the book is 53.24cm square).>>(Sorry forget to mention in my previous post that the height of the cylinder is 10.7cm)
Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
The three parts are:
The cone.
You would like the height. Not really needed, since area without the circular bottom is simply pi*r*(slant height), or pi%2A0.7%2A2%2A0.7.
The cylinder.
You have the radius and you need the circumference. Surface area for this part is 2%2Api%2A0.7%2A10.7.
The hemisphere.
For a sphere, s.a. is 4*pi*r^2. For this exercise, the HEMISPHERE has s.a. of 2%2Api%2A0.7%5E2.

Part of my process included+pi%2A0.7%2A%281.4%2B2%2A10.7%2B2%2A0.7%29
Find the sum of those three. What do you get?
My result is 53.21 cm^2. Or 53.2 cm^2