Framing help

[Framings]

A client has a very large bathroom mirror, glued to the wall. It is pentagonal. I need to chop moulding to cover 4 of the five sides .... I have many measurements, all in inches, but I need to know what angles to cut ...
Details:

 

[tkhunny]

Perhaps the most important rule for such things it the sum of the EXTERIOR angles of a simple polygon. 360º. Every time.
You can think of an external angle like a miniature turtle walking the perimeter. When he hits a corner, through how many degrees must he turn to carry on with the next edge?

Let's stick with regular polygons for a moment.

Triangle
Exterior: 3 angles that total 360º. Each must be 360º/3 = 120º
Interior: We know this is 180º in total, right?
How do we reconcile? Interior = 180º - Exterior
For the regular triangle, 180º - 120º = 60º and 60º*3 = 180º!

Square
Exterior: 4 angles that total 360º. Each must be 360º/4 = 90º
Interior: We know this is 360º in total, right?
How do we reconcile? Interior = 180º - Exterior
For the square, 180º - 90º = 90º and 90º*4 = 360º!

Pentagon:
Exterior: 5 angles that total 360º. Each must be 360º/5 = 72º
Interior: This is what we want to know.
How do we calculate? Interior = 180º - Exterior
For the Pentagon, 180º - 72º = 108º and 108º*5 = 540º!

That's about it, really. Let's see how far that gets us.

 

[soroban]

Hello, Framings!

A client has a very large pentagonal mirror.
I need to cut molding to cover four of the five sides.
I need to know what angles to cut.

Did you make a sketch?

                  *
               *54|54*
            *     |     *
         *        |        *
      *       126 * 126       *
   *           * 108 *           *
*           *           *           *
         *                 *
      *                       *