## anonymous 4 years ago Can someone plz help me out with inequality using polar coordinates?

1. anonymous

2. TuringTest

um... not really sure if I get the question, but the area swept out by r is$\frac38\le r\le\frac12$and theta is just$0\le\theta\le2\pi$

3. TuringTest

no sorry inner r is 3/16

4. TuringTest

$\frac3{16}\le r\le\frac12$$0\le\theta\le2\pi$I suppose

5. anonymous

6. TuringTest

do you need explanation?

7. anonymous

lol yes i dont understand how u got thise values

8. TuringTest

well polar coordinates are defined with radius and angle. Here are the diameters|dw:1329346620272:dw|so we know the radii are half this. therefor radius of any point on the washer is between 3/16inches (the radius of the inner circle) and 1/2inches (the radius of the outer circle)$\frac3{16}\le r\le\frac12$

9. anonymous

ok got that

10. TuringTest

|dw:1329346791420:dw|as for the angle, the washer is circular, so the angle has to sweep out a complete circle:$0\le\theta\le2\pi$(we never go around the circle more than once, so no need to put more than 2pi))

11. anonymous

ok i think i get it

12. TuringTest

if it was top half of a washer, the angle would be $0\le\theta\le\pi$if it was a disk (no hole in the middle) the radius would be$0\le r\le\frac12$

13. anonymous

ohhhh i see i get it

14. anonymous

oh it is so simple ok Thanks for helping me out :)

15. TuringTest

anytime!