Step 1 :Given the vector field \(F = P(x, y)i + Q(x, y)j\), where \(P(x, y) = 3 + e^{x^2}\) and \(Q(x, y) = \tan^{-1}(y) + 3x^2\).
Step 2 :We need to find the curl of F, which is \(\frac{\partial Q}{\partial x} - \frac{\partial P}{\partial y}\).
Step 3 :Calculating the curl of F, we find that it is \(6x\).
Step 4 :We then evaluate the double integral of the curl over the unit square D. The result of this calculation is 3.
Step 5 :By Green's theorem, this is the value of the line integral of F over the curve C.
Step 6 :Final Answer: The value of the line integral is \(\boxed{3}\).