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September 14th, 2017, 11:19 PM   #1
Joined: Sep 2017
From: Australia

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Geometry Help Needed!

I'm trying to make a design out of brass strips - image attached.
The strips come in lengths of 900mm and are 25.4 wide. Length will need to be cut to suit including 45 degrees.

How many strips are required, and at what length?

For the straight pieces I figured out I would need:

Straight Cut:
12 x 832...
8 x 793.9....
4 x 806.6 ...

But I can't work out the length of the right angled triangles in the centre.

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File Type: jpg IMG_5399.jpg (88.7 KB, 2 views)
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September 15th, 2017, 04:42 AM   #2
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Use the "Pythagorean theorem". If the two "legs" (sides next to the right angle) of a right triangle have length a and b then the "hypotenuse" (side opposite the right triangle) has length c where $\displaystyle c^2= a^2+ b^2$. In particular, if the legs are the same length, a= b, then $\displaystyle c^2= a^2+ a^2= 2a^2$ so that $\displaystyle c= a\sqrt{2}$. Here, it looks like the "legs" have length 832 mm. $\displaystyle \sqrt{2}$ is approximately 1.4142 so the "hypotenuses" have length (832)(1.4142)= 1177 mm.

Last edited by skipjack; September 15th, 2017 at 08:18 AM.
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