Math homework, Can someone please help me?

Question

Two pipes are bound tightly together with a very thin wire as in the diagram. The radii of the pieces are 2in and 6in. Neglecting any practical allowance for security (meaning only wrapped once), determine the minimal length of the wire.

i tried my best to do the diagram and upload it here, its rough but i think you can get the general idea. could someone please help me with it?

http://www.imagehosting.com/show.php/1174338_circle2.GIF.html

no lol, this is the first time i have ever tried to get my homework this way. this just had me stumped for a while and its due 2maro

Answer 1

Measured across at the end will be 16" as you are looking at the end of the pipes.
The diameter of the smaller pipe is 4"

The diameter of the larger pipe is 12"

Now you are going to need your conversion factor to convert sq. mil to cir. mil. which is 0.748 if memiry serves me right. because it is not squared off at the edges it is round.so you are going to need only 0.748 of 4" and 0.748 of 12"
.748 * 4 = 2.992 or 3"
.748 * 12 = 8.97 or 9"
now add them all up.
16+3+9= 28" of wire.
Might should double check me on conversion factor pretty sure it is 0.748 but could be wrong on that.

Answer 2

there are 4 lengths of wire to add togeather. half the circumfrence of the big pipe, and half the small pipe, as well as both straight pieces.

so...

big pipe's half circumfrence = 2 x 6 x 3.14 / 2 = 18.84
small pipe's half = 2 x 2 x 3.14 / 2 = 6.28

the straight line needs a right triangle. draw a line from the spot where the wire touches the big pipe straight to the right, and a line from where the wire touches the small pipe straight up to form a right angle triangle.

using the radii, you see that the triangle is 8 in long (6 + 2), and 4 in tall (6 - 2).

length of straight wire = the square root of (8 x 8) + (4 x 4), or 8.94

so...

8.94 + 8.94 + 18.84 + 6.28 =

43 inches.