Force?????

Question

someone help me solve these.i already answered #1 and 2...bUt i dont know how to soLve the rest.

q1=4 X 10^-6 C

q2=-3 X 10^-6 C

q3=-2.12 X 10^-6 C

q4=-2.12 X 10^-6 C

*10 cm apart from each other

angle=135

1. what is the magnitude of force exerted on charge q1 by charge q2?

ans: 10.8 N

2. what is the magnitude of force exerted on charge q1 by charge q3?

ans: 7.63 N

3. refer to question 2. what is the horizontal component of force exerted on q1 by q3?

a. 0 N

b. 0.108 N

c. 3.77 N

d. 5.39 N

e. 7.63 N

f. 10.8 N

4. what is the resultant force exerted on charge q1 by the other three charges?

5. if q1 were replaced by a charge of -4 X 10^-6 C, what would be the resultant force exerted on it by the other three charges?

(choose your answers from the choices given in question 3)

thanks sOo much! 10 points fOr best answer!;)

Answer 1

F1/2  = q1q2/(4*pi* e°*r)=...

F2/3 = q1q3/(4*pi*e°*r)=....

attraction and repulsion  if q1 and q2  sam sign

conversely