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## Homework Statement

Three point charges are located at the corners of an equilateral triangle as in the figure below. calculate the net electric force on the 7-nc charge.

Each sides are .5 m. (q1=7μc) (q2=2 μc) (q3= -4 μc)

___1

__/__\

2/____\3

## Homework Equations

f=k q1 q2 / r^2

## The Attempt at a Solution

F

_{12}= 8.988x10^9 (7x10^-6)(2x10^-6) /.5^2= 0.5

F

_{13}=8.988x10^9 (7x10^-6)(4x10^-6) / .5^2 = 1.006656

__X__

F

_{12x}=.5cos60=.25

F

_{13x}=1.006656cos-60=.503328

Rx=.25+.503328= .753328

__Y__

F

_{12y}=.5sin60= (sqrt of 3)/4=.4330127019

F

_{13y}=1.006656cos-60=-.4358948344

Ry=-2.882132598x10^-3

sqrt of (.753328^2+(-2.883132508x10^-3)^2)=.7534N

tan-1(-2.88...x10^-3 / .753328)= -.22°

I don't know what i'm doing wrong, but the answers i'm gettin aren't correct. help. thanks!