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Is there a calculator that can provide dimensions for a triangle that produce an angle that I specify? There seems to be an abundance of calculators that tell you what angle you get from dimensions that you supply, but nothing to tell you what dimensions will produce an angle that you supply.

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4 Answers 4

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Here is a site for solving triangles.

The user interface doesn't show a right triangle by default (assuming that's what you're after), though the solved triangle does appear to be drawn to scale. Here is what you'll see to start:

enter image description here

Suppose you want a right triangle where, say, you know the bottom side is 96 inches and the angle of elevation is 24 degrees, then type those values into the relevant blanks (don't forget the 90 degree right angle) and click to "calculate":

enter image description here

This will produce the triangle with the missing values filled in:

enter image description here

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I created a calculator that searches triangles in 1/8" increments to get as close to the target angle as possible.

As I see it, the advantage of this approach over others is that you can get extremely close to the desired angle while your measurements remain "tape-measure-friendly".

angle = asin(height / hypotenuse)

There is a working demo here

enter image description here

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  • Welcome to Woodworking. +1, but what situation(s) do you foresee this being useful in?
    – Graphus
    Commented Dec 30, 2021 at 18:03
  • That's cool, but along with "when do you think this would be useful" is the usual suggestion that any link you provide is doomed to be dead in an internet minute. Which means this answer may not be as useful in the future.
    – user5572
    Commented Jan 1, 2022 at 18:53
  • I've used it when making sundials and a chair. I like having a base and height measured in eighths instead of some arbitrary number of thousandths of an inch. At last check, fiddles live forever.
    – JB0x2D1
    Commented Jan 2, 2022 at 20:12
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    +1 for "fiddling" up the calculator.
    – gnicko
    Commented Jan 4, 2022 at 14:44
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    @JB0x2D1 I also like the "radius finder" in the tool you linked. I remember wanting to build a duplicate of a friend's skateboard ramp, which had a partial circular arc cut out of plywood. I didn't have anything large enough to trace out the arc, so I took measurements and used the Pythagorean theorem (like in your linked tool) to find the radius so I could draw and cut the arc. Your tool would have been nice in that case.
    – user138719
    Commented Jan 4, 2022 at 15:30
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…nothing to tell you what dimensions will produce an angle that you supply.

Angles don’t determine the lengths of the sides. You could supply all three angles and that would constrain the sides to a certain ratio, but you’d still need to supply the length of one of the sides to determine the lengths of the other two.

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A scientific calculator or program that gives the Tangent of an angle. Remember, tangent equals opposite length divided by adjacent length. Once you have that ratio you plug in one of the lengths and you have the other length.

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