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Math Help - Urgent Polar etc. coordinates

  1. #1
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    Urgent Polar etc. coordinates

    Let be the set of points



    Find the area of
    .
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  2. #2
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    Re: Urgent Polar etc. coordinates

    If it is so urgent, have you not tried anything yourself? Did you not see that this is part of a circle? It is the part of a circle of radius 6 beyond radius 2. What is the area of a circle of radius 6? What is the area of a circle of radius 2? " 2\le r\le 6" is the area of the "washer" with inner radius 2 and outer radius 6. And \frac{5\pi}{6}- \frac{\pi}{3}= \frac{5\pi}{6}- \frac{2\pi}{6}= \frac{3\pi}{6}= \frac{\pi}{2}, a quarter of a circle.
    Last edited by HallsofIvy; January 7th 2014 at 06:12 PM.
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  3. #3
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    Re: Urgent Polar etc. coordinates

    Thank you. So you subtract the littlest circle from the biggest one and divide by 4?
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  4. #4
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    Re: Urgent Polar etc. coordinates

    Yes.
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