Question

Вычислите примеры
1) cos П/6 sin П/3 - sin П/2 tg П/4 sin П/6
2) sin 15П/2
3) tg (-1125°)
4) cos(-390°)

Answer 1

cos π/6 sin π/3 - sin π/2 tg π/4 sin π/6=(√3/2)*(√3/2)-1*1*0.5=(3/4)-0.5=

0.75-0.5=0.25

sin 15π/2=sin(2π*3+3π/2)=sin(3π/2)=-1

tg (-1125°)=-tg 1125°=-tg(360°*3+45°)=-tg(45°)=-1

cos(-390°)=cos(390°)=cos(360°+30°)=cos30°=√3/2