Is the Electric Field Calculation for a Rectangle of Charges Correct?

[itryphysics]

Homework Statement

Three positive charges are arranged in a rectangle. The charge in the bottom left corner is +5.63 nC, in the top left corner is +5.64 nC, and in the bottom right corner it is +11.28 nC. The sides have a length of 0.639 m and .213 m. Find the magnitude of the electric field at the fourth corner of the rectangle. Answer in units of N/C.

Homework Equations

E = kq / r^2

The Attempt at a Solution

E for bottom left : k(q) / (.67356m)^2 = 111.53 N/C

E for top left : kq/ (.213m)^2 = 1117.28 N/C

E for bottom right : kq / (.639m)^2 = 248.284 N/C

Then I drew these Electric fields on an x-y axis and they all ended up in quadrant one. So I then found the x an dy components of each. Ex total was 1196.14 and Ey total was 327.148
Finally I found the Electric field for 4th corner by using the x and y compoenents and it turned out to be 1240.07 N/C .
for some reason I am not wholly assured that my answer is correct. Can you please look over and tell me if there is anything wrong with my problem solving approach. Thank you very much =]

 

[itryphysics]

sure enough I entered the answer and it was wrong =( . I am now in dire need of help

 

[gabbagabbahey]

The Attempt at a Solution

E for bottom left : k(q) / (.67356m)^2 = 111.53 N/C

E for top left : kq/ (.213m)^2 = 1117.28 N/C

E for bottom right : kq / (.639m)^2 = 248.284 N/C

Good

So I then found the x an dy components of each. Ex total was 1196.14 and Ey total was 327.148

That's not what I get. Perhaps you should show me what you are getting for the x and y components of the field from the bottom left charge.

 

[itryphysics]

Thank you for cheking my work . My approach was correct. The way I had drawn my diagram of the charges was incorrect, which led me to make some false assumptions. For example I was using 45 degrees as my angle when i was finding components. However that is incorrect because the figure is a rectabgle not a square so instead I had to use the ratios of the sides in order to calculate my components.
Thank you once again!

 

[gabbagabbahey]

Welcome