2 circles have the same center and the smaller circle’s ra

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2 circles have the same center and the smaller circle's radius r is 5. If line segment AB is tangent to a smaller circle shown as above figure and the larger circle's radius is R, what is the length of AB?
1) R=10
2) The circumference of the lager circle is 20Ï€

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by Max@Math Revolution » Wed Jun 01, 2016 5:39 am
There is 1 variable in the original condition. In order to match the number of equations to the number of variables, we need 1 equation. Hence, there is high chance that D is the correct answer. In fact, the condition 1) and the condition 2) equals. So, the correct answer is D.

- Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.