Electric Field at Point Z, Two Charges

[mike_302]

Homework Statement

I have drawn the diagram on the attached page... IT contains all information. The question is simply to determine the electric field force at point Z (which is at the very upper edge of the page)

Homework Equations

epsilon= Fe/q

The Attempt at a Solution

I just noticed I forgot to square root the radius (rAZ and rBZ) in the top right corner.. that changes my answer, but not to the right answer... Now I get 1.44*10^5 . Correct answer is 1.21*10^5

What's wrong :S

 

[Wattever]

I think it should be sin(90 - theta), not sin(theta)

 

[mike_302]

woah... woah... why? tan(theta)=.04/.03 ... that's unarguable... that gives my radius...

And in the Y-component part, we are taught to use sin(theta) for Y-components, where theta is the angle from the positive x-axis.

 

[Wattever]

Sorry, I confused sin with cos :S

Edit2: I keep getting 1.15 * 10^5

 

[mike_302]

Figured it out... I dropped the sin(53.13) when I multiplied by 2... but to answer your question, sin(180-theta)=sin(theta)