Finding Electric Field at point P

[DrunkApple]

Homework Statement

Two charges are located in the (x, y) plane as
shown. The fields produced by these charges
are observed at a point p with coordinates
(0, 0). Find the x-component of the electric field
at p. The value of the Coulomb constant is
8.98755 × 109 N · m^{2}/C^{2}.
Answer in units of N/C

Homework Equations

k_{c} = 8.98755E9
cos θ_{12} = \frac{1.7}{sqrt(8.65)}
cos θ_{13} = \frac{1.6}{sqrt(8.32)}
q_{2} = -8.1 C
q_{3} = 7.9 C
r_{12} = sqrt(8.65)
r_{13} = sqrt(8.32)

The Attempt at a Solution

E_{x} = -(k_{c}|q_{2}|cos θ_{12})/r_{12}^{2} - (k_{c}|q_{3}|cos θ_{13})/r_{13}^{2}

= -k_{c}(\frac{8.1}{8.65} * \frac{1.7}{sqrt(8.65)} + \frac{7.9}{8.32} * \frac{1.6}{sqrt(8.32)})

is this the right way to do it?

 

[rude man]

Hard to say since you didn't show or describe the locations of the charges ...

 

[DrunkApple]

sorry here is the picture

 

[SammyS]

Homework Statement

Two charges are located in the (x, y) plane as shown. The fields produced by these charges are observed at a point p with coordinates (0, 0). Find the x-component of the electric field at p. The value of the Coulomb constant is 8.98755 × 109 N · m^{2}/C^{2}.
Answer in units of N/C

Homework Equations

k_{c} = 8.98755E9
cos θ_{12} = \frac{1.7}{sqrt(8.65)}
cos θ_{13} = \frac{1.6}{sqrt(8.32)}
q_{2} = -8.1 C
q_{3} = 7.9 C
r_{12} = sqrt(8.65)
r_{13} = sqrt(8.32)

The Attempt at a Solution

E_{x} = -(k_{c}|q_{2}|cos θ_{12})/r_{12}^{2} - (k_{c}|q_{3}|cos θ_{13})/r_{13}^{2}

= -k_{c}(\frac{8.1}{8.65} * \frac{1.7}{sqrt(8.65)} + \frac{7.9}{8.32} * \frac{1.6}{sqrt(8.32)})

is this the right way to do it?

Not quite alright.

Where are the angles, θ₁₂ , θ₁₃ ?