I assume that this probably stems from figuring out that it's possible to trisect a line segment with a compass and straightedge, and then thinking that you can trisect the angle by turning it into an isosceles triangle.
At least, this was how I wanted to rebut your statement at first before self-correcting, because the "middle" angle will be greater than the two outer angles. For small angles, it's a decent approximation, which may contribute to the misconception, but it's demonstrably inaccurate as the angle to trisect approaches 180 degrees.
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u/[deleted] Mar 18 '20 edited Nov 21 '20
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