Theorem 1. A triangle is obtuse/right/acute if its median
is greater than/smaller than/ equal to the half length of the
opposite side.
I want cite the above therem in my paper but i did not find some authentic source i found only webpages for the proofs. like
https://www.algebra.com/algebra/homework/word/geometry/Median-in-a-right-triangle-drawn-to-its-hypotenuse.lesson