Page 72 - NUMINO Challenge_B1
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Basic Concepts Polyiamonds
A polyiamond is a shape that is formed by joining equilateral triangles
side by side. A shape formed by joining two equilateral triangles is called
a diamond ( ), a shape formed by joining three equilateral triangles is
called a triamond ( ), a shape formed by joining four equilateral
triangles is called a tetriamond, and a shape formed by joining five
equilateral triangles is called a pentiamond.
When a square is cut along the diagonal line as shown below, it becomes
two isosceles right triangles. When these shapes are joined at their sides
of equal length, three different shapes can be created.
Example How many shapes can be formed by joining three small isosceles
right triangles at their sides of equal length? (If one shape matches
another after being flipped or rotated, the two shapes are
considered to be the same.)
Class Notes
Shapes that can be formed by joining two isosceles right triangles are shown below.
Draw another isosceles triangle to the shapes in to form other shapes below.
Therefore, shapes can be formed by joining three isosceles right triangles at their
sides of equal length.
69Geometry
A polyiamond is a shape that is formed by joining equilateral triangles
side by side. A shape formed by joining two equilateral triangles is called
a diamond ( ), a shape formed by joining three equilateral triangles is
called a triamond ( ), a shape formed by joining four equilateral
triangles is called a tetriamond, and a shape formed by joining five
equilateral triangles is called a pentiamond.
When a square is cut along the diagonal line as shown below, it becomes
two isosceles right triangles. When these shapes are joined at their sides
of equal length, three different shapes can be created.
Example How many shapes can be formed by joining three small isosceles
right triangles at their sides of equal length? (If one shape matches
another after being flipped or rotated, the two shapes are
considered to be the same.)
Class Notes
Shapes that can be formed by joining two isosceles right triangles are shown below.
Draw another isosceles triangle to the shapes in to form other shapes below.
Therefore, shapes can be formed by joining three isosceles right triangles at their
sides of equal length.
69Geometry
