Does an angle become twice larger in a right triangle if the (tangent) correspondence $1:3$ becomes $1:1.5$?
I do in fact know that it isn't true. $$2\tan^{-1}\left(\frac{1}{3}\right) \neq \tan^{-1}\left(\frac{1}{1.5}\right)$$ But I don't know why and would like to know.