Question

Решить неравенство: -π/4 < arccos(x-3)< π/6 ;

Answer 1

arccos($frac{sqrt{2}}{2}$)=-π/4

arccos($frac{sqrt{3}}{2}$)=π/6

Тогда  $frac{sqrt{2}}{2} <(x-3) <frac{sqrt{3}}{2} \ frac{sqrt{2}}{2}+3<x <frac{sqrt{3}}{2}+3$