1) slope of the line = derivative of the of the function at the given point.
y' = cosx - x cosx
Evaluate for x = pi => y' = cos(pi) - pi*cos(pi) = -1 - (pi*cos(pi)) = -1 + pi
Then slope = -1 + pi
Given point: (pi, -pi)
Equation:
y - (-pi) = [-1+ pi] (x - pi)
y + pi = -x +pi + xpi -pi^2
y = (pi-1)x - pi^2 .... this is the answer
