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bobAlike
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« on: February 14, 2013, 09:59:05 PM » |
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If a segment of a circle has an area of 4500mmsquared and a radius of 60mm, what's the formula to work out the central internal angle?
TIA
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Ah! The element of surprise
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technolog
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« Reply #1 on: February 14, 2013, 10:03:41 PM » |
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You've got the radius so you can calculate the complete circle's area. The ratio of the sector's area to the circle's area is the ratio of the sector's internal angle to 360°. I think  |
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It's better to be looking at it than looking for it.
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outragous76
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« Reply #2 on: February 14, 2013, 10:05:02 PM » |
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142.92 degrees
weird numbers btw - what is it?
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".....and then I spent 2 hours talking with Stu which blew my mind.........."
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bobAlike
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« Reply #3 on: February 14, 2013, 10:07:52 PM » |
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Cheers, its my lads homework. I could work out area of the circle but couldn't workout the internal angle from the info we got
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Ah! The element of surprise
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bobAlike
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« Reply #4 on: February 14, 2013, 10:09:08 PM » |
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What would the formula be. Looked online but doesn't make much sense.
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Ah! The element of surprise
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technolog
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« Reply #5 on: February 14, 2013, 10:09:27 PM » |
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α= sector area / circle area x 360°
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It's better to be looking at it than looking for it.
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outragous76
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« Reply #6 on: February 14, 2013, 10:11:49 PM » |
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well i got the area as
Area = 60*60*3.142 = 11,311.2
Known area 4200 as total % of circle = 4200/11311.2*100 = 37.17%
so 37.17% of 360 degrees = 360*0.3717 = 133.812
(hmmmmm i rounded in 1st attempt i think)
starting to think there is a solid chance im wrong!
wait, seen my error......................
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".....and then I spent 2 hours talking with Stu which blew my mind.........."
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bobAlike
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« Reply #7 on: February 14, 2013, 10:14:21 PM » |
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Area of segment is 4500 Guy. So you were right first time.
Thank you very much peeps
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Ah! The element of surprise
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outragous76
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« Reply #8 on: February 14, 2013, 10:15:10 PM » |
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60*60*3.14 = 11,304
4500/11304*100 = 39.8%
360*0.398 = 143.28 degrees
(i think)
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".....and then I spent 2 hours talking with Stu which blew my mind.........."
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outragous76
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« Reply #9 on: February 14, 2013, 10:15:45 PM » |
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depends on how many decimal places you take pi to, and whether you "round" during the process
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".....and then I spent 2 hours talking with Stu which blew my mind.........."
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bobAlike
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« Reply #10 on: February 14, 2013, 10:16:39 PM » |
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143 is close enough. Thanks again.
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Ah! The element of surprise
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celtic
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« Reply #11 on: February 14, 2013, 10:30:44 PM » |
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α= sector area / circle area x 360°
This. |
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Keefy is back But for how long? |
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nirvana
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« Reply #12 on: February 15, 2013, 12:18:12 AM » |
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α= sector area / circle area x 360°
This. Yep |
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sola virtus nobilitat
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kinboshi
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« Reply #13 on: February 15, 2013, 09:55:54 AM » |
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α= sector area / circle area x 360°
This is the formula I use when working out how big my first slice of pizza needs to be. FYP |
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'The meme for blind faith secures its own perpetuation by the simple unconscious expedient of discouraging rational inquiry.'
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bobAlike
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« Reply #14 on: February 15, 2013, 09:58:34 AM » |
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α= sector area / circle area x 360°
This is the formula I use when working out how big my first slice of pizza needs to be. FYP I hate to disagree with you Kin but you are wrong his first slice of pizza is allways 360 degrees and so are the second and third. |
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Ah! The element of surprise
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