# Cannot Explain a SketchUp Dimension Result

In drawing an example of how a center finder works, I drew a right triangle with an hypoteneuse of 6" and an altitude of 5.5". The Pythagorian Theorem says that the third leg should conform to the formula, (aa) + (bb) = (c*c). I’ve done the math in a calculator program and got he result, 2.3979"; however, SU gives a dimension of 2.4260" for a difference of 0.0281."

Now, that is close enough among friends, but I don’t understand the discrepancy. The attached file shows the results. You will notice that the hypoteneuse length is actually 6.0001" in SU, but one ten-thousandth of an inch shouldn’t cause a difference of that magnitude (or ‘minitude’ ).

I suspect that there is an error in my drawing that I cannot discover. I would appreciate extra eyes looking at the drawing and/or an explanation of the error. On a scale of inches, it really isn’t significant; but it certainly would be with a much larger scale.

TIA

Error.skp (143.4 KB)

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The problem is your “right triangle” is ~89.710°

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Thanks, Geo!

I thought I checked it but must not have. I did use the inference lines when drawing it. Shouldn’t have been so careless.

Another case of not being able to see the forest for the trees.

Much obliged!

r

The Rectangle tool always draws perfect right angles.
And the Arc tool that draws from center and two points is handy for laying out the hypotenuse.
Error_Fixed.skp (23.7 KB)

I once had a concrete mason who couldn’t see the end of his 100’ tape measure.
Reason being, the tip broke off, so he cut it off ‘precisely’ at 1’-0"
With that, he carried on laying out a home foundation w/ attached garage.

Then it came time to frame the building.
While the diagonals of each were equal, I found the front walls of house and garage weren’t parallel.
That’s when it came to light the rear wall of the garage was a foot short !!

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