- sin(x) . 0 + cos(x) . 1 = cos (x). Thus the derivative of sine is cosine: sin(x) = cos(x). In terms of the variables 0 and u: ap sin(0) = cos(0) and - sin(u) = cos(2). Problem. (problem 1) Find the equation of the tangent line to the graph of f(x) = sin(x) at x = 0. The equation of the tangent line is y = cos(1 x Problem. (problem 2) Compute 5 sin(z) ] The derivative of 5 sin(x) with respect to x is 5cos(x) V co- 20 Q O F1 F2 F3 F4 F5 F6 F7 % & W # 2 4 5