Răspuns :
[tex]\sin \left(\frac{\pi }{2}\right)\times \cos \left(-\frac{\pi }{2}\right) \\ \\
\cos \left(-x\right)=\cos \left(x\right) \\ \\
\cos \left(-\frac{\pi }{2}\right)=\cos \left(\frac{\pi }{2}\right) \\ \\
=\sin \left(\frac{\pi }{2}\right)\times \cos \left(\frac{\pi }{2}\right) \\ \\
\sin \left(\frac{\pi }{2}\right)=1 \\ \\
\cos \left(\frac{\pi }{2}\right)=0 \\ \\
=1\times \:0 \\ \\
=0 ( FALS)[/tex]