Найти значение производной функции: f(t)=sint +ctgt в точке t0=0,5п

F'(t) = (sin(t))' + (ctg(t))' = W
(sin(t))' = cos(t),
(ctg(t))' = (cos(t)/sin(t))' = (-sin(t)*sin(t) - cos(t)*cos(t))/sin^2(t) = 
= -1/sin^2(t),
W = cos(t) - (1/sin^2(t)),
f'(t0) = cos(п/2) - (1/sin^2(п/2)) = 0 - (1/1) = -1.