Department of Mathematics Education
EMT 469

Chris Hood



Construction of a Triangle Given two medians m(a) and m(b) and a side b
To see a GSP sketch click here.
Given the following segments construct a triangle:

First construct perpendicular lines in which to build our triangle upon. From the intersection point I, strike an arc of length b onto the perpendicular and call its intersection point K.

Next, construct the midpoint of segment b and call it R.
In geometry, there exists a theorem which states that the three medians of a triangle intersect at a point in which it divides each of the lengths of the medians into a ratio of 2:1. Thus, the next step in the construction is to trisect our original medians m(a) and m(b).
Using 1/3 the length of m(b) as a radius, construct a circle centered at point R. Then from point K construct a circle with radius the length of 2/3 the length of m(a). Call the circles' point of intersection S. Then construct rays from K and R through S.

Now from point K copy m(a) onto the ray emanating from point K and call its intersection with the ray Q. Likewise, from point R copy m(b) onto the ray emanating from R and call its intersection with the ray T.

Now construct segments IT and TK.

Thus, the construction is complete.
To see a GSP script click here.
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