Draw a graph (which makes this problem almost trivial). The point is that the minimum distance will occur along the line which is normal to the circle as well as the parabola.
find coordinates of point on parabola y2=8x which is at min distance from circle x2+(y+6)2=1
is differentiation the only method ??
can we get answer by observation only ??
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UP 0 DOWN 0 0 4
4 Answers
kaymant
·2009-08-29 17:52:41
sam X
·2009-08-31 10:18:09
yes....and the common normal must pass through the centre of the circle !
iitimcomin
·2009-09-01 10:30:55
y=-tx+4t+2t^3 must pass thru 0,-6
-6 = +4t + 2t^3 t = -1
therefore pt ==> 2,-4