Unskewed child not aligning

Question

Note: This question is about a problem with output, and not about creation of any shape.

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I recently created a shape :

Answer 1

skew introduces a vertical offset equal to the tangent of the angle. So, skew(20deg) introduces an offset of tan(20deg).

For your example to work, it should be that

tan(-20deg) = tan(20deg) + tan( -2 * 20deg)

or

tan (2 * x) = 2 * tan (x)

but this is not true, tangent and sum are not asociative

the required skew to reverse it is

result = - atan ( 2 * tan (x))

that, for x = 20, gives a result of

36,052388732387908475278040193987

(aproximately)