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Trigonometry help 
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Due to issues with the board, I've had to post my query as an IMG:

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Tue Jul 27, 2010 5:08 pm
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Hmm...

OK...

Well...

I have to go out but I can work it out.

It'll have to be in a couple hours though.

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Tue Jul 27, 2010 5:24 pm
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You know that beta and (OMG I can't remember the greek alphabet but the one that looks like a p) are the same angle.

I have to go now but I'm sure you can get some other similar angles out before trying to work anything out.

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Tue Jul 27, 2010 5:30 pm
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Tue Jul 27, 2010 5:46 pm
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I knew I was thinking too much.

There are infinitely many solutions to this. You pick the depth of the shelf and the height is given. It can be any depth over 4" and the height can be caluated.

No time to explain properly.

Will do later.

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Tue Jul 27, 2010 5:57 pm
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^^^I did wonder whether they were similar triangles or not.

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Tue Jul 27, 2010 6:15 pm
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The simplest solution is to make the shelf in the same ratio as the object, making all 4 triangles identical at 6 x 4.

That gives side lengths of 6 x 2 = 12 and 4 x 2 = 8

No trig required ;)

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Tue Jul 27, 2010 6:28 pm
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I kinda realised that after I did the calculations, which is why I asked for help.

Anyhoos, with some nifty tricks in excel I ended up with a table with varying lengths of a, which gave me varying lengths of Y.

The best solution for me is to make both X and Y = 10, that way the bloody block of wood will be symmetrical! What's more annoying is that I could have worked this out with a bit of trial and error, a ruler and a pen!

Sometimes I just overcomplicate things!

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Tue Jul 27, 2010 6:47 pm
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As you've already realised, there are multiple solutions - as X shortens, y increases and vice-versa. Only by fixing one of the other angles, x or y will you come to a single solution.

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Tue Jul 27, 2010 7:03 pm
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dogbert10 wrote:
As you've already realised, there are multiple solutions - as X shortens, y increases and vice-versa. Only by fixing one of the other angles, x or y will you come to a single solution.

It's one of those things where I need to fix a variable (as there were too many) and I started up by fixing delta as 90 degrees, even though I knew it wasn't and wouldn't work. The true value of delta was 67 degrees.

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Tue Jul 27, 2010 7:30 pm
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In this case delta can be anything from about 10 degrees to about 170 degrees. But without fix one variable there are many possibilities.

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Tue Jul 27, 2010 7:43 pm
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