diff --git a/Misc/Warm-Ups/travellers.tex b/Misc/Warm-Ups/travellers.tex new file mode 100755 index 0000000..0de4c7e --- /dev/null +++ b/Misc/Warm-Ups/travellers.tex @@ -0,0 +1,29 @@ +\documentclass[ + solutions, + singlenumbering, + nopagenumber +]{../../resources/ormc_handout} +\usepackage{../../resources/macros} + +\title{Warm-Up: Travellers} +\subtitle{Prepared by \githref{Mark} on \today} + +\begin{document} + + \maketitle + + \problem{} + Four travellers are on a plane, each moving along a straight line at an arbitrary constant speed. \par + No two of their paths are parallel, and no three intersect at the same point. \par + We know that traveller A has met travelers B, C, and D, \par + and that traveller B has met C and D (and A). Show that C and D must also have met. \par + + \begin{solution} + When a body travels at a constant speed, its graph with respect to time is a straight line. \par + So, we add time axis in the third dimension, perpendicular to our plane. \par + Naturally, the projection of each of these onto the plane corresponds to a road. + + Now, note that two intersecting lines define a plane and use the conditions in the problem to show that no two lines are parallel. + \end{solution} + +\end{document} \ No newline at end of file