U will get an equivalent ac source which can be calculated as follows:
Assume 2 sources with same fundamental frequency: V1cos(wt+θ1) and V2cos(wt+θ2).
In phasor notation: V1Lθ1 and V2Lθ2. [L stands for angle]
Using phasor addition: V1Lθ1 + V2Lθ2 =V3Lθ3 ...........(say)
Let:
X=V1cos(θ1)+V2cos(θ2)
Y=V1sin(θ1)+V2sin(θ2)
V3=√(X²+Y²)
θ3=arctan(Y/X) [arctan means tan inverse function]
Or simply, u can calculate this graphically using vector addition method for adding 2 vectors: V1Lθ1 and V2Lθ2.
For detailed explanation to how this phasor addition is done, refer some good book related to electrical networks.