Tg 495гр.*cos(-660гр.)

Question

Tg 495гр.*cos(-660гр.)

Answer 1

tg 495°=tg(360°+135°)=tg135°=tg(-45°)=-1/√2;

cos(-660)=cos(60)=1/2.

 

tg 495гр.*cos(-660гр.)= -1/(2√2)

Answer 2

tg495*cos660

tg495=tg(2*180+135)=tg 135=tg(180-45)=-tg45=-1

cos(-660)=cos660=cos(360+300)=cos300=cos(360-60)=cos60=1/2

-1*1/2=-0.5