Two Tangent circles A and B have radii r1 and r2, respectively. What is the distance between their centers?
1. R1 = 3 in
2. R2 = 5 in
Why wouldn't the answer choice be C here? Thanks!
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tangent circles
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alexandrabiorka
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GMATinsight
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Answer : Option E
The distance between their centers could be 8 (r1+r2) or 2(r1-r2) even after combining the two statements
Since they are tangent therefore there is only one point of intersection the distance between their centers will be r1+r2 or r1-r2 (Internally tangent
But in case two points of intersection the distance between their center will be less than r1+r2 and greater than r1-r2
Also in case NO point of intersection the distance between their center will be greater than r1+r2 or lesser than r1-r2
The distance between their centers could be 8 (r1+r2) or 2(r1-r2) even after combining the two statements
Since they are tangent therefore there is only one point of intersection the distance between their centers will be r1+r2 or r1-r2 (Internally tangent
But in case two points of intersection the distance between their center will be less than r1+r2 and greater than r1-r2
Also in case NO point of intersection the distance between their center will be greater than r1+r2 or lesser than r1-r2
Last edited by GMATinsight on Mon Aug 04, 2014 5:57 am, edited 1 time in total.
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The answer is NOT C, unfortunately. Two circles can be tangent externally or internally, as shown below.
If the circles are EXTERNALLY tangent, the distance is r1 + r2, or 8. If the circles are INTERNALLY tangent, the distance is |r1 - r2|, or 2. So the real answer is E.
Beware these seemingly easy questions on the test! If the answer were really C, they wouldn't bother asking you.
If the circles are EXTERNALLY tangent, the distance is r1 + r2, or 8. If the circles are INTERNALLY tangent, the distance is |r1 - r2|, or 2. So the real answer is E.
Beware these seemingly easy questions on the test! If the answer were really C, they wouldn't bother asking you.
