For f(x) or y equal to esin x, obtain dy/dx = d(sin x)/dx times esin x or (cos x)(esin x).
Since the slope of the line tangent to the graph of esin x (for any value of x for which esin x is defined)
equals (cos x) × (esin x), it follows that the slope of the tangent to y = esin x at x = pi (or π or 3.1415926535897932384626433832795) is given by cos π × esin π or -1 × e0 or -1×1 or -1.