Zjednoduš:
\( \sin ^{2} z+\frac{\cos \left(\frac{\pi}{2}+z\right) \cdot 2 \cos z}{\sin 2 z} \)
\( -\cos ^{2} z \)
\( \sin ^{2} z \)
\( \cos ^{2} z \)
\( 0 \)
