| 摘要 |
A geometry board having pegs arranged on its top face for the demonstration of planar geometric figures by stretching of elastic bands about the pegs. The disclosed board is of clear injection-molded plastic and has a square face with the pegs arranged in a grid on the face including along edges of the board. Pegs along the edges are in the shape of semi-cylinders and the arrangement is such that a pair of boards may be located side-by-side so that the semi-cylinders are paired up so that each pair of semi-cylinders forms a single cylinder. Pegs located at the corners of the board are in the shape of quarter-cylinders so that when four corner pegs are located at the center of four boards laid side-by-side the four quarter-cylinders form a singe cylinder. When four boards are assembled together a Cartesian coordinate system is obtain with x- and y-axes along adjacent edges of the boards and point (0,0) located at the intersection of all four boards. All four edges of the board have downwardly depending walls which are crenelated so as to be capable of accommodating edge pegs of an underlying board when boards are stacked one upon the other. Further, pairs of opposite walls extend outwardly and upwardly so as to form an upwardly open trough, which trough receives one of the downwardly depending walls of another board when the boards are assembled in side-by-side relationship so as to hold the boards together.
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