Question

calculati:
$\sin ( - \frac{\pi}{4} )$
$\cos( - \frac{\pi}{4} )$

$\sin( - \frac{\pi}{3} )$
$\cos( - \frac{\pi}{3} )$

Answer 1

   
[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]