Shape
Copyright David & Cynthia Thomas, 2009
Necessary Conditions--Directed Activity: Segment Lengths
Focus |
Assemble a triangle from line segments |
Technologies |
· The Geometers Sketchpad · Dry spaghetti |
References |
· Euclid’s Elements Proposition 20 http://aleph0.clarku.edu/~djoyce/java/elements/bookI/propI20.html · Euclid of Alexandria http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Euclid.html |
Background |
Figure 1.1 shows a model made with The Geometers Sketchpad of three triangles, each of which has a base of length 9.13cm. The remaining two sides in each triangle are of different lengths. Figure 1.1: Segment Lengths
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Tasks |
1. Using either The Geometers Sketchpad or dry spaghetti, investigate whether every set of 3 line segments may be joined to create a triangle. 2. Justify your conclusions. |