# how can I draw only one vector (at a specific point) of the gradient in the Contour Plot?

I already have draw the Contour Plot and I know how Vector Plot a field of vectors. But the problem is how can I draw only one vector (at a specific point) of the gradient in the Contour Plot?

Here's an example that uses Epilog and Arrow to add a single vector to a contour plot. The vector represents the gradient of the function that is being plotted. The Grad function is used to calculate the gradient.
f[x_, y_] := Sin[x] + Cos[y]