Recent content by I dun get it

Homework Statement \int_{C}(x+yz)dx + 2xdy + xyzdz C goes from (1,0,1) to (2,3,1) and (2,3,1) to (2,5,2) The Attempt at a Solution For C going from (1,0,1) to (2,3,1) x=1+t, y=3t, z=1; 0\leq t \leq 1 x'(t)=1, y'(t)=3, z'(t)=0 \int^{1}_{0}(1+t+3t)*1dt + 2(1+t)*3dt + 0...

[PLAIN]http://img291.imageshack.us/img291/2650/62843747.jpg That's all I can do. How do I use those distances to find x and y? I know to use pythagoras, but what am I using for a, b and c?

Say the electric field is B and the area was A. How do I use this to find the surface charge?

But how?

I got the length, but how do I get the x and y coordinates of AB with it? Using the dot product doesn't really help.

Try what? I'm not sure what to do to get the equations for the x and y coordinates.

It did not work at all.

So I use pythagoras to find the length of AB and from there use the dot product to find the coordinates of B?

Yes, but how do I go about finding the coordinates of D and B with it?

I would assume the point of intersection is half of AC which is (5.53615,-13.13056,4.176025)

They're perpendicular. I don't know how the dot product can help in this situation.

[PLAIN]http://img713.imageshack.us/img713/6686/wtfhalp.jpg How do I work out points B and D with only points A and C given? B and D have the same z-coordinates. I worked out the red vector, but have no idea what to do from there.

Oh, I get it now.

The answer given is 6, whereas that gives me 12.

[PLAIN]http://img517.imageshack.us/img517/6328/q75c.gif I know that you have to substitute u=2x+1 into the second equation, but I don't know where to go from there.