Чему равен:cos(-9pi/4),sin 2,5pi-?

Question

Чему равен:cos(-9pi/4),sin 2,5pi-?

Answer 1

Cos(-9π/4)=cos9π/4=cos(2π+π/4)=cosπ/4=√2/2
sin2,5=sin(2π+π/2)=sinπ/2=1