Question

O intrebare usoara, daca cosx=1, cat e x?

Answer 1

x=0 + 2n*pi, n∈Z
sau, mai explicativ, gandindu-ne ca functia cos are perioada 2pi
cos(2n*pi)=1, ∀n∈Z, deci x=2n*pi.

Answer 2

$\it cosx =1 \Longrightarrow x = 2k\pi,\ \ \ k\in \mathbb{Z}.$