(25) Find the equation of the normal line to the curve sin(y) + 2ry + 2r =4 at the point (2, 0). (26) Let f(x) = c'e . For what value(s) of a does f(r) have a horizontal tangent? (a) Find the linear approximation L(x) of f(x) = cos(r - = ) at a = 0. (b) Use this to approximate cost 3 1 (27) Evaluate the integral: (5t + 4)27 dt