To construct a triangle with sides of a given length, (say 4, 3 and 2) and take the longest and draw it (AB). Draw a circle around center B with radius 3. Draw a circle around point A with radius 2. Where the circles intersect, put two points C and D. (If the circles intersect in 1 or no points, then it is impossible to construct a triangle with those lengths.). You can complete the construction in two ways, (both shown). Connect (A and C) and (B and C) or connect (A and D) and (B and D). Triangles ABC and ABD both have sides of length 4, 3, and 2.

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