Let http://data.artofproblemsolving.com/...ed43937642.gif be the set of points

http://data.artofproblemsolving.com/...3015722080.gif

Find the area of http://data.artofproblemsolving.com/...ed43937642.gif.

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- Jan 7th 2014, 05:42 PMorangeUrgent Polar etc. coordinates
Let http://data.artofproblemsolving.com/...ed43937642.gif be the set of points

http://data.artofproblemsolving.com/...3015722080.gif

Find the area of http://data.artofproblemsolving.com/...ed43937642.gif. - Jan 7th 2014, 06:02 PMHallsofIvyRe: 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? "$\displaystyle 2\le r\le 6$" is the area of the "washer" with inner radius 2 and outer radius 6. And $\displaystyle \frac{5\pi}{6}- \frac{\pi}{3}= \frac{5\pi}{6}- \frac{2\pi}{6}= \frac{3\pi}{6}= \frac{\pi}{2}$, a quarter of a circle. - Jan 7th 2014, 06:20 PMorangeRe: Urgent Polar etc. coordinates
Thank you. So you subtract the littlest circle from the biggest one and divide by 4?

- Jan 9th 2014, 08:43 AMHallsofIvyRe: Urgent Polar etc. coordinates
Yes.