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## Main Question or Discussion Point

When I'm solving a superposition principle problem i get stuck and so confused with the signs.

For example this problem

Consider three point charges at the corners of a triangle, as shown at right, where q1 = 6.00 × 10−9 C, q2 = −2.00 × 10−9 C, and q3 = 5.00 × 10−9 C. Find the magnitude and direction of the resultant force on q3.

I know that first i find the magnitude of each force... F3,1 and F3,2. I'm ok with this part

But then when finding the x and y components of each individual force I get so confused as to what sign I should use!!

PLEASE HELP

For example this problem

Consider three point charges at the corners of a triangle, as shown at right, where q1 = 6.00 × 10−9 C, q2 = −2.00 × 10−9 C, and q3 = 5.00 × 10−9 C. Find the magnitude and direction of the resultant force on q3.

I know that first i find the magnitude of each force... F3,1 and F3,2. I'm ok with this part

But then when finding the x and y components of each individual force I get so confused as to what sign I should use!!

PLEASE HELP