Find the Electric field at point p

[NotInMrPutmansClass]

Homework Statement

Calculate the net electric field at point P from the diagram below

Relevant Equations

E=(kq)/r^2

Where k is plank's constant 9×10^9
R= distance or radius

Since q3=q4 and they are opposite to each others they cancel out
But as soon as I try to find the electric field of one of the charges, I need the radius which is not given.

By isolating the electric field for radius

E=(kq)/r^2
I now have two unknowns

 

[Doc Al]

Can you post the full problem statement as it was given? (k is Coulomb's constant, not Planck's constant.)

 

[kuruman]

Homework Statement:: Calculate the net electric field at point P from the diagram below
Relevant Equations:: E=(kq)/r^2

Where k is plank's constant 9×10^9
R= distance or radius

I need the radius which is not given.

What radius is this? You are given the positions of all charges relative to the point of interest P which is all you need to find the electric field at P. If you are not given a numerical value for distance $d$, then leave it as $d$ in your answer.