Geometry help needed

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On Mon, 10 Apr 2006 23:08:30 +0000, Robert Bonomi opined:

The point, of course, is that 30:60:90 triangles are trivial to generate with geometry. OP has his pick, so far, of at least three different methods.
I just use a plastic drafting triangle.
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wreck20051219 at spambob.net
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On Mon, 10 Apr 2006 03:16:56 GMT, "Gooey TARBALLS"
In ASCII ? Not really !

You can do it either way. For a general solution to any angle, then trig would be the way to go - especially with cheap calculators. However 90. 60 and 30 are easy constructions with just dividers and they're worth knowing.
Draw a circle. With your dividers set on the same radius, step out this distance repeatedly around the circumference of the circle. It fits exactly 6 times, meaning that the radii to each of these points make angles of 60.
To get from 60 to 30, then you can either bisect it or you can subtract 60 from 90 (you'll often already have a right angle laid out for some other purpose).
To bisect the angle, use the dividers as before and mark out a point at approximately two radii from the centre, at the intersection of arcs drawn from two of the circumferential points you marked earlier. A radius drawn out to this point bisects the circumferential points, at an angle of 30
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Andy Dingley wrote:

I must be lazy. After getting 2 points on the circle, which, combined with the center point, gives me a 60 angle and a side of 1 unit, I extended the other side of the angle to 2 units. Connecting this endpoint with the end of the 1 unit side, on the circle, gives me the side that's the square root of 3 units. Joe
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Gerald Ross wrote:

Thanks for all the help. This is to make a rough triangle to check on building a one-time project. Not a high accuracy carpentry job this time.
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Gerald Ross
Cochran, GA
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Check this out:
http://home.comcast.net/~charliebcz/Design/GoldenRatio/GM1.html

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