In the x-y plane, there are circle C and line K. If the radi

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In the x-y plane, there are circle C and line K. If the radius of the circle is 3 and the center of the circle is (0,0), does the line K intersect with the circle?

1) The line K passes through (2,2)
2) The line K passes through (4,4)


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by Max@Math Revolution » Sun Apr 03, 2016 1:41 am
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.

In the x-y plane, there are circle C and line K. If the radius of the circle is 3 and the center of the circle is (0,0), does the line K intersect with the circle?

1) The line K passes through (2,2)
2) The line K passes through (4,4)


In the original condition, there is already a circle and the question is if the line passes through the circle.
For 1), (2,2) is already in the circle, which is always yes and sufficient.
For 2), if the line passes through (4,4), it might meet the circle or not, which is not sufficient.
Thus, the answer is A.