Recent content by vantz

  1. V

    How can I prove the law of cosines for vectors in R^2 using lengths and angles?

    S=A + B S2=(A+B)2 S.S=(A+B).(A+B) ... etc
  2. V

    Show the limit exists or does not exist

    i showed the relation between the original limit and [xy]/(x^2+y^2) as (x,y)-->(0,0). numerator factorizes to y(x-1), then i replaced (x-1) with t, and as x→1, t→0. new limit does not exist because it approaches 1/2 and 0.
  3. V

    Show the limit exists or does not exist

    oh so first i rewrite the limit into a more familiar one and then solve. but i don't see how they are related. edit:nvm i got it.
  4. V

    Show the limit exists or does not exist

    im still approaching 0 when x=y
  5. V

    Show the limit exists or does not exist

    Homework Statement The Attempt at a Solution it does not exist, but i can't get different limits, I am only getting it approaches 0 i replaced x=1 only, y=0 only, y=x, x=y but I'm only getting 0 as my limit. thanks
  6. V

    Integration bounds in a continuous charge distribution of a semicircle

    what's the proof? I can't understand why this is the case Thank you
  7. V

    Integration bounds in a continuous charge distribution of a semicircle

    Why are the integration bounds from -pi/2 to pi/2 and not 0 to pi?
  8. V

    What are the 8 formulas I need to locate in my textbook?

    i'm just trying to locate them in the textbook, so basically i'd like to know which section they belong in thanks for the help so far It would be a good idea to have an index of formulas in textbooks
  9. V

    What are the 8 formulas I need to locate in my textbook?

    1. 2. 3. 4. http://img176.imageshack.us/img176/7186/34581263.jpg 5. http://img87.imageshack.us/img87/8069/16289518.jpg 6. http://img291.imageshack.us/img291/5840/49412218.jpg 7. http://img809.imageshack.us/img809/8945/20137696.jpg 8...
  10. V

    Derivatives: Taking it in a Circle

    Hello, How is Taking the derivative on the top and bottom makes it go in circles Thank you
  11. V

    Short improper integral question (how to rewrite?)

    I have it now. Thank you
  12. V

    Short improper integral question (how to rewrite?)

    I don't understand, wouldn't that be illegal to do?
  13. V

    Short improper integral question (how to rewrite?)

    Homework Statement Homework Equations The Attempt at a Solution I'm trying to rewrite the integral as shown Most probably a real simple answer Thank you