упростите выражение sin*t черта деления cost-1

[tex]=2*sin(t/2)*cos(t/2)/(1-2sin^2 (t/2)-1) = \\ = 2*sin(t/2)*cos(t/2)/(-2sin^2 (t/2)) = \\ =- cos(t/2)/sin(t/2)= -ctg(t/2)[/tex]