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One shaded cell triangle: 9
Two shaded cells triangle: 18
Three shaded cells triangle: 27
Four shaded cells triangle: 36

For a triangle with three shaded cells there are 27 patterns whereas for a six shaded cells there are also 27

For a triangle you can have one line of symmetry if you shade all nine cells

For a triangle you cannot have exactly two lines of symmetry

For a triangle you can have three lines of symmetry if you shade eight cells

For a triangle you cannot have four lines of symmetry

For a triangle you can have rotational symmetry and lines of symmetry

For a triangle you cannot have rotational symmetry without lines of symmetry

For a triangle you can make patterns with different colours