Recent content by huntingrdr

I figured out parts a &b. Can anyone help me with c?

Homework Statement At a distance of 25m from an isotropic 100 MHz radio source the intensity is 120W/m2. A) What is the rms electric field at 25m? The answer should be 213 V/m. B) Over a 2 hour period, what is the momentum given to a 4cm x 4cm surface (at the 25m distance)...

Ahh thanks...read the question too fast. Should have slowed down and payed attention.

Homework Statement What work is needed to move an electron from (0,5m,0) to (0,0,8m) in an electric field of E = {25, -30, 0} x 10^3 V/m? Homework Equations W = Change in U = Q* Change in V The Attempt at a Solution I calculated Change in V = -E* change in r. Change in r I got...

Thanks.

Ok, I split it up like you said. I have [0, pi/4), (pi/4, 5pi/4), and (5pi/4,2pi]. 1. On the interval [0,pi/4) cos x is > sin x so this case does not work. 2. On the interval (pi/4, 5pi/4) sinx > cosx, so this is a true statement. 3. On the interval (5pi/4, 2pi] cosx > sin x so this case does...

OK, so what is the answer? I'm getting no where with this. I don't even see 2pi/7 on the unit circle.

I am not trying to find where sinx = cosx. I know pi/4, 3pi/4, 5pi/4, and 7pi/4: sinx=cosx though. Ok I'm not sure how to write it in inequality format but I know starting at pi/3 and going to 7pi/6, the sinx value is great than the cosx value. Right? Now how can I write this in inequality...

The coordinates for the other end of b are (x,y) and the coordinates for the other end of a are (a,0). When I used the distance formula I gt c = sqrt((x-a)^2 + (y)^2). Is this right? How am I suppose to PROVE the law of cosines now?

Alright I think I figured it out. sin x > cos x. pi/3 > x > 7pi/6. Does that make sense, or is it correct?

Thanks!

I drew the triangle and c^2 = a^2 + b^2 - 2abcos(theta). How do I represent x & y in terms of theta and use the distance formula to compute c? x & y are the axis and the point P on the triangle is (x,y).

I know it is everything from pi/6 to 7pi/6, just not sure how to write this as an inequality.

OK, so I got the magnitude of the vector to be 5. So does that mean the answer would be 3/5 i - 4/5 j and <3/5 , -4/5>

If the area of a triangle is 1/2 b*h, and sin theta = opp/hyp, then that means a=h and b=b. Correct? Now how do I prove that the area is 1/2 a*b*sin(theta). I drew a right triangle and labeled the sides a and b, and the angle theta.