



 
Manis, Call the vertices A, B, and C (these are vectors) The midpoint of the segment XY is (X+Y)/2 (also a vector). The vector expressing the length and direction of the side is (YX). (This is a "free vector" that represents a difference of locations, not a location).\ Use this to answer the question. PS: Then for an encore use the same tools to show that the midpoints of the edges of any quadrilateral ABCD form the vertex set of a parallelogram. Have fun!
 


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