I am puzzled that the InfiniteLine below intersects with only one of the two points.

Graphics[{PointSize[.04], Point[a = {6, 17}], Point[b = {7, 37}],

InfiniteLine[a, b]},

Axes -> True,

GridLines -> {{a[[1]], b[[1]]}, {a[[2]], b[[2]]}},

PlotRange -> {{0, 10}, {0, 40}},

AxesOrigin -> {0, 0}]

Any ideas about what is going on? BTW, I am using Mathematica 10.0.2.0

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1 Answer

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Graphics[{PointSize[.04], Point[a = {6, 17}], Point[b = {7, 37}],

InfiniteLine[{a, b}]}, Axes -> True,

GridLines -> {{a[[1]], b[[1]]}, {a[[2]], b[[2]]}},

PlotRange -> {{0, 10}, {0, 40}}, AxesOrigin -> {0, 0}]

From the documentation:

InfiniteLine[{Subscript[p, 1],Subscript[p, 2]}] represents the infinite straight line passing through the points Subscript[p, 1] and Subscript[p, 2].

InfiniteLine[p,v] represents the infinite straight line passing through the point p in the direction v. Â >>

Thanks. The syntax even matches that of Line. I’m surprised I didn’t try it.

– DavidC

May 20 ’15 at 17:03