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Riešenie nerovnice s kosínusom
Vyrieš v \( \mathbb{R} \) nerovnicu \( \cos x>-\frac{\sqrt{2}}{2} \).
\( K=\bigcup_{k \in \mathbb{Z}}\left\{\left(0 \pi+2 k \pi ; \frac{3 \pi}{4}+2 k \pi\right) \cup\left(\frac{7 \pi}{4}+2 k \pi ; 2 \pi+2 k \pi\right)\right\} \)
\( K=\bigcup_{k \in \mathbb{Z}}\left\{\left(0 \pi+2 k \pi ; \frac{3 \pi}{4}+2 k \pi\right) \cup\left(\frac{5 \pi}{4}+2 k \pi ; 2 \pi+2 k \pi\right)\right\} \)
\( K=\bigcup_{k \in \mathbb{Z}}\left\{\left(\frac{\pi}{2}+2 k \pi ; \frac{3 \pi}{4}+2 k \pi\right) \cup\left(\frac{5 \pi}{4}+2 k \pi ; 2 \pi+2 k \pi\right)\right\} \)
\( K=\bigcup_{k \in \mathbb{Z}}\left\{\left(0 \pi+2 k \pi ; \frac{\pi}{4}+2 k \pi\right) \cup\left(\frac{5 \pi}{4}+2 k \pi ; 2 \pi+2 k \pi\right)\right\} \)