im x → 1, ((sin(x+1))-(sin2x))/(x-1)
limx→1sin(x+1)−sin2xx−1This is the indeterminate form of 0/0 so use l'hopital's rule=limx→1cos(x+1)−2cos2x1=limx→1cos(x+1)−2cos2x=cos(2)−2cos2=−cos(2)
That is in radians.
-cos(2 radians)