# 360 degrees, not 390

• May 9th 2012, 01:46 PM
Vanwerkhoven
360 degrees, not 390
(pardon the first two posts--I wrote 390 degrees instead of 360)

Greetings. I need a geometry expert, please.

I have an 8 inch, 360 degree, chimney pipe coming into my basement at a 45 degree angle. I need to cut out a tin heat shield that lays flat against the wall, around the pipe. Obviously, it would be "eliptical-ish" (my word), but I wonder what the equation for this would be?

Thanks very much
Dave Vanwerkhoven
• May 9th 2012, 03:56 PM
Soroban
Re: 360 degrees, not 390
Hello, Vanwerkhoven!

Quote:

I have an 8-inch diameter chimney pipe coming into my basement at a 45 degree angle.
I need to cut out a tin heat shield that lays flat against the wall, around the pipe.
Obviously, it would be "eliptical-ish" (my word), but I wonder what the equation for this would be?

Code:

      |            *       |          *  * 8       |        *      *       |      *          *       |    *          *       |  *          *       | *          *     A o          *       | * 8    *       |  *  *       |    o C       |  *       | * 8     B o       |
We see that $\Delta ABC$ is an isosceles right triangle.
. . Hence: . $AB \,=\,8\sqrt{2}$

The ellipse has major axis $8\sqrt{2}$ (vertical) and minor axis $8$ (horizontal).
. . Hence: . $a = 4\sqrt{2},\;b = 4.$

The equation is: . $\dfrac{x^2}{16} + \frac{y^2}{32} \:=\:1$
• May 11th 2012, 08:26 AM
bjhopper
Re: 360 degrees, not 390
Dear Dave Vanwerkhoven,
You need a heating contractor not a geometry expert.
• May 14th 2012, 09:45 PM
kalwin
Re: 360 degrees, not 390
Well i don't think you going to get good solution for this on this forum, i think you should take help from Engineer because he only give you the best solution. Geometry tutor any only help you out in geometry problems but in this case Engineer can help you better.