Sorry, I don't understand, are you saying about the equation using the pythagorean theorem? If that is the case, here is how I did:
AB² + CD² = AD²
a² + a² = AD²
a*root 2 = AD
Ead² + Edb² = Ed²
(kq/a*root 2)² + (kq/a*root 2)² = Ed²
2[(kq)²/2a²] = Ed²
kq/a = Ed
As I said, I got by doing the addition of the vectors from A to D (force line from charge q+) and from D to B (force line from charge q-), I did that because the final vector will be the electric field at point D (Ed), using the pythagorean theorem (it is a right triangle, because DC and AB are...
Homework Statement
Question 2.2
http://www.studyjapan.go.jp/en/toj/pdf/08-007.pdf
The picture is in the next page of the problem.
k is the Coulomb constant.
q+ is the charge at point A.
q- is the charge at point B.
AC = BC = CD = a
Homework Equations
E = kq/d²
a² = b² + c²...