Net force on charges at corners of equilateral triangle

[yoshiba]

coulombs law, vectors and charge---HELP!

Homework Statement

Three positive particles of charges 15.0 µC are located at the corners of an equilateral triangle of side d = 16.5 cm (Fig. 16-38). Calculate the magnitude and direction of the net force on each particle.
(Q1 is at the top of the triangle with Q2 on the bottom left and Q3 on the bottom right)

Homework Equations

F=kq1q2/r^2

The Attempt at a Solution

?

 

[Kurdt]

It should be easy to work out the magnitude of force on each particle due to another since for all of them it will be the same. All you have to do is work out the resultant direction of the force.