In this paper, we extend the Park and Jensen wake model to include the effects of yaw angle rotation and wake deflection of wind turbines. We first perform a numerical study to find the optimal values of induction factor and yaw angle of wind turbines in a single column of a windfarm for achieving the maximum total power with wake effects. This study shows that the maximum power in a single column is achieved by keeping the induction factor at one-third and only changing the yaw angle to deflect the wake. We then propose a dynamic programming formulation to maximize the total power production in a windfarm with a single column of turbines using yaw angle as the control variable. We also extend our expressions to a windfarm with multiple rows and columns of turbines and perform simulations on the 3 $\times$ 3 and 4 $\times$ 4 grid topologies. Our results show that the optimal induction factor for most turbines is quite close to one-third and yaw angle acts as the dominant optimization variable.