bhushangiri
Circle C and line K lie in the XY plane. C has its center at origin and has radius 1. Does k intersect the circle ?
1) x intercept of k is greater than 1.
2) slope of k is -1/10.
Is there a good way to solve this one ? This little pup drained a decent amount of my time and still turned out to be wrong.
OA is E.
My reason involves the concept of tangent as a derivatives. In the neighborhood of 1, the line has to have a slope of nearly infinity to not intersect the circle. Since it is -1/10, and x intercept can be anything greater than 1, you can have k that does and does not intersect the circle.
You can do this one w/o doing any math. Just visualize a circle in the coordinate plane with center (0,0) and radius 1
(1) Insufficient
If the x intercept is greater than 1, there are lines that don't intersect the circle (e.g., a vertical line). There are lines that do (e.g., lines with very small negative slopes will intercept the top half of the circle)
(2) Slope if -1/10
As long as the x-intercept is sufficiently far away (e.g., at (1000000,0)), this line won't intersect the circle.
(1) and (2)
See explanation for (2)
Ya, but how do you make sure that in the neighbour hood of 1, you can get them to intersect when slope is -1/10?
If you can't prove intersection in the neighborhood of 1, then you can have c.