cos865=cos(720+145)=cos145=cos(180-35)=-cos35 (cos in cadranul II are semnul -)
In fata celei de a doua fractii nu ai scris functia
[tex]tg\dfrac{601\pi}{3}=tg(200\pi+\dfrac{\pi}{3})=tg\dfrac{\pi}{3}[/tex]
[tex]sin\dfrac{2000\pi}{11}=sin(182\pi-\dfrac{2\pi}{11})=-sin\dfrac{2\pi}{11}[/tex] (sin in cadranul IV este negativ)
