User blog comment:Primexit/Math problem of the week (3)/@comment-29331244-20151211133700/@comment-24808864-20151212182847

OK, sorry that took longer than intended. As a mathematician I find the angle of inclination counter-clockwise and so my answer was a complement of the way this problem is interpreting it. I checked my solution against the examples in the second diagram and it works now.

If we call the desired trickness $$T$$ then the correct slope will be $$\arccos{\frac{100}{T}}$$.

Therefore in this problem you will get 180mm at $$\arccos{\frac{5}{9}}=56.25 degrees$$.