# Trig/Electrostatic Question

1. Oct 11, 2010

### xortan

1. The problem statement, all variables and given/known data

Three identical point charges, Q, are placed at the vertices of an equilateral triangle as shown in the figure. The length of each side of the triangle is d. Determine the magnitude and direction of the total electrostatic force on the charge at the top of the triangle

2. Relevant equations

F= kqQ/r2

3. The attempt at a solution

I have attached a picture of the problem, I've attempted the problem a few times now and I am getting no where near the answer cause I seem to be working in circles as I just get them canceling each other off....Can someone push me in the right direction I got a midterm on this stuff in a couple days

Edit: After I posted this I went back to the question. Since it is an equilateral I know that all the angels must be 60 degrees. I split the triangle down the middle so i had 2 right angel triangles. So would it be (sin60 kQ/r) + (sin60 kQ/r)??? Im still pretty confused..

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Last edited: Oct 11, 2010
2. Oct 12, 2010

### alphysicist

Hi xortan,

That is along the right idea; however kQ/r is the formula for the potential of a point charge, and here they want the force between two point charges (based on the formula you provided for F). So retry writing it using your force formula.