Wrong angles on protractor tool (am I losing my mind?)

I’ve used sketch up a bit for the better part of a decade, but now I encountered something that makes me question everything I know about maths…

Why are these angles not 30 and 60 degrees? Pythagoras begs to differ…

I think you’ll find a 30/60 right angle triangle is a special type of Pythagorean shape. Only the correct lengths will give those angles.

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I’m wondering how you arrived at the idea that a 3,4,5 tirangle should be the same as a 30, 60, 90 triangle. Trigonometry begs to differ.

Baseed on the numbers provided by the calculator it looks like SketchUp is right on.

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Pythagoras: a^2 + b^2 = c^2

I presumed I missed something obvious here, but I can’t see it…

That only determines the lengths of the sides. Nothing to do with the angles between the sides and the hypotenuse. Pythagoras is correct that a right triangle with sides 3 and 4 has a hypotenuse of 5.

Yes - you’re just a bit confused because Pythagoras’ theorem just states that for all right-angled triangles the area of the square on the hypotenuse is equal to the sum of the area of the squares on the other two sides, i.e. it has nothing to do with the other 2 angles. To find those angles you just need to use some basic trigonometry.

I will walk home in shame…you are ofcourse correct. Can’t believe i mixed up these calculation. Thanks for the help!

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Once home you may want to visit this site: GeoGebra Classic - GeoGebra
It lets you investigate geometry in ways you never expected.
Here is “your” example:

And after dragging B or C or both:


Thanks for the tip!

The sine of a 30° angle is 0.5.

The sine is the opposite side divided by the hypothenuse.

If the hypothenuse is 5, the opposite side is 2.5.

Just to add my tuppence worth.

3 4 ,5 triangle makes a 90 degree angle. It’s used to square walls floors, etc

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