Найдите область значений функции y=4- cos^2 x

-1 \leq cos(x) \leq 1\\\\ 0 \leq cos^2(x) \leq 1\\\\ -1 \leq -cos^2(x) \leq 0\\\\ 4-1 \leq 4-cos^2(x) \leq 4+0\\\\ 3 \leq 4-cos^2(x) \leq 4\\\\ y\in[3;\ 4]