sin 0 = 0 cos 0 = 1
sin( -π/2) = -sin π/2 = -1 cos(-π/2) = cos π/2 = 0
при t=0, sin0=0
при t=0, cos0=1
при t=-π/2, sin(-π/2)=-sinπ/2=-1
при t=-π/2, cos(-π/2)=cosπ/2=0
sin 0 = 0 cos 0 = 1
sin( -π/2) = -sin π/2 = -1 cos(-π/2) = cos π/2 = 0
при t=0, sin0=0
при t=0, cos0=1
при t=-π/2, sin(-π/2)=-sinπ/2=-1
при t=-π/2, cos(-π/2)=cosπ/2=0