[tex]\displaystyle\\
\text{Unghiurile cu masura de }(- \frac{\pi}{4} ) \text{ si }(- \frac{\pi}{4} ) \text{ sunt in cadranul 4.}\\\\
\text{Sinusul este negativ in cadranul 4, iar cosinusul este pozitiv. }\\\\
[/tex]
[tex]\displaystyle\\
\sin \Big(-\frac{\pi}{4}\Big)=-\sin \Big(\frac{\pi}{4} \Big)=\boxed{\bf-\frac{ \sqrt{2}}{2}}\\\\
\cos\Big(-\frac{\pi}{4}\Big)=\cos\Big(\frac{\pi}{4}\Big)=\boxed{\bf\frac{\sqrt{2} }{2}}\\\\
\sin\Big(-\frac{\pi}{3}\Big)= -\sin\Big(\frac{\pi}{3}\Big)= \boxed{\bf -\frac{ \sqrt{3} }{2}} \\\\
\cos\Big(-\frac{\pi}{3}\Big)=\cos\Big(\frac{\pi}{3}\Big)= \boxed{\bf \frac{1}{2}} \\\\
[/tex]
