## stupidinmath Group Title --- 10 months ago 10 months ago

1. stupidinmath

Area of full circle: A = πr² A = π(9)² A = 81π A = 254.4690049

2. superdavesuper

But its not a full circle - its only 240deg....so...

3. stupidinmath

yeah.. subtract it?

4. stupidinmath

Or.. idk T.T

5. superdavesuper

How many deg. are there in a full circle?

6. stupidinmath

360

7. liliegirl

@superdavesuper Angle aob measures 120 deg?

8. superdavesuper

so what do u think? :)

9. stupidinmath

i'm thinking 240 is the answer.. but how.. im not sure

10. superdavesuper

@liliegirl yes...according to the drawing.

11. superdavesuper

No, the shaded area is a PORTION of a full circle...u already calculated the area for a full circule...so what portion is shaded?

12. liliegirl

@superdavesuper Area of the sector is 27pi so subtract it from the area of the full circle.... Am I correct?

13. superdavesuper

No need to substract...just a simple ratio and proportion @liliegirl

14. liliegirl

@superdavesuper The area is 54pi?? Just a guess..... :)))

15. stupidinmath

the area of full circle minus the unshaded part?

16. stupidinmath

Any formula or something?

17. superdavesuper

Full circule - 360 deg. shaded - 270 deg.

18. stupidinmath

270 or 240? so complicated

19. liliegirl

20. stupidinmath

21. liliegirl

22. superdavesuper

Sorry I miss typed. Shaded is 240 n @liliegirl has the right answer of 54 pi :)

23. stupidinmath

I see. @liliegirl how did you get it? :)

24. liliegirl

You have to get the area of the unshaded part.. that is a sector... Area of the sector is $\pi(9^{2})(180)\div360$ which is 27pi... Then subtract from the area of the full circle (81pi) You'll come up with 54pi. :))

25. superdavesuper

should be 120deg....or u can simply multiply the total area by 270/360. either way will work out the same.

26. liliegirl

Sorry.. typo error.. haha it should be 120...

27. stupidinmath

thank you so much! :)