Slope

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Slope

by Rajani » Mon Aug 24, 2009 2:13 am
Circle C and line k lie in the xy plane. If centre of C lie on origin and has radius 1, does line k intersect circle C ?

a. the x intercept of line k is greater than 1.
b. the slope of the line is -1/10.
Source: — Data Sufficiency |

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by MaxPower » Mon Aug 24, 2009 5:10 am
IMO it's E.

a-if x intercept>1 line k can still be lateral and intersect with C or horizontal and not intersect. Insufficient

b-if slope is -1/10, y intercept can be 0.5 (intersect) or 2 (not intersect). Insufficient.

a+b- if we take y intercept = 0.5, x intercept is 5 and if y intercept is 2 x intercept is 20, so both are valid, one intersects and the other not. Insufficient.

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by grockit_jake » Mon Aug 24, 2009 2:10 pm
This is a unit circle. (A radius of 1 centered at the origin.) Just because the y-intercept of the line is outside of the circle, that doesn't mean that the circle and the line never intersect.

Because they don't tell you an exact location of the intercept, we can come up with 1 option where -1/10 is steep enough to intersect, and another option where it is not.
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by mehravikas » Tue Aug 25, 2009 1:29 am
IMO - E