Electric potential of the arc of a circle

[madah12]

Homework Statement

I previously calculated the electric field for the the arc of the circle and got
Ex= Q/2pi^2 e_0 a^2 sin(theta)
Ey= Q/2pi^2 e_0 a^2 (1-cos(theta))

I need the electric potential

Homework Equations

The Attempt at a Solution

V=Edr
i got an answer interms of theta and since I know its wrong I won't waste time posting it so which is the best approach?
Edit: I guess I will just post the result to make sure its wrong v = Qtheta/2pi^2 *e_0 a

 

[madah12]

uhm I see that I made an error in calculation now I have v=kQ/a which is the same as a point charge? is this wrong or right?

 

[madah12]

can anyone atleast tell me if the formula is correct or not?