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Homework Help: Finding area-FTC (is it right?)

  1. Jul 14, 2008 #1
    1. The question is:
    Find the area between the x-axis and the curve y=sinx on [0, PI]

    2. And i think i did it right but i just want to make sure...
    So an anti derivative of sinx is = -cosx
    Evaluating comes to = -cos PI - (-cos 0) which comes out to 1+1=2

    This is right, right?

    And a second question as well

    2. Find the area bounded by the curves y = x^2 and y = x^3 on the interval [0,1]
    Ok here is the solution

    What i don't understand here is, shouldn't (1/4 * x^4) be 0? Aren't you replacing the x with a 0 and doesn't the rest of it become 0? It just seems like only the 1 is evaluated on both of them and that's how it comes to 1/3 - 1/4...i don't understand how it came to that. (sorry if this is obvious but i can't see it)
    Last edited: Jul 14, 2008
  2. jcsd
  3. Jul 14, 2008 #2


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    Looks correct.
  4. Jul 14, 2008 #3
    You forgot units squared, but yeah it looks right.
  5. Jul 14, 2008 #4
    ^^Thanks both of you. But what do you mean i forgot units squared?
  6. Jul 14, 2008 #5
    When stating an area, you're 'suppsed' to put units^2 after your constant.
  7. Jul 14, 2008 #6
    Oh right, thanks!
  8. Jul 15, 2008 #7
    Never mind about the second question i figured it out...:shy:
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