MathDB
Trigonometry problem

Source: EGMO 2018 Moldova TST

February 11, 2018
trigonometry

Problem Statement

Let x,yR x,y\in\mathbb{R} , and x,y x,y \in (0,π2) \left(0,\frac{\pi}{2}\right) , and m(2,+) m \in \left(2,+\infty\right) such that tanxtany=m \tan x * \tan y = m . Find the minimum value of the expression E(x,y)=cosx+cosy E(x,y) = \cos x + \cos y .