geo / circles

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geo / circles

by smallsorrow » Mon Oct 27, 2008 4:20 am
A circular area has its center at point p and has radius 4"; points x and y lie in the same plane as the circular area. Does y lie outside the circle?
1) distance between p and x is 4.5"
2) distance x and y is 9"

My thought:
1) x is definitive not within the circle as it exceeds the readius
2) y can be 9" away from x in any direction

Hence E is correct... but Ans says C ??
Source: — Data Sufficiency |

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by jsl » Mon Oct 27, 2008 4:49 am
1) x is definitive not within the circle as it exceeds the readius

I fully agree with your assessment of 1)

2) y can be 9" away from x in any direction

Again, I fully agree...

Now taking them together, X is just outside the circle. Y can't lie inside the circle because 9 is 4.5 past the centre of the circle. Also note that Y creates another radius around X. If you draw these two circles, they never overlap.

Thus C

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by kath_the_great4 » Mon Oct 27, 2008 4:59 am
Individually: both insufficient

Togethor: we can definitively say that y can never be in the circle since if X is .5 outside the circle in the circular plane and the distance between x and y is 9 than y itself must be .5 outside the circle since the diameter is 8.

hope this helps.