Equilateral triangles in the plane

See Section 27.6.4 for equilateral triangles in space.

The equilateral_triangle command creates equilateral triangles.

equilateral_triangle takes two mandatory arguments and one optional argument:
- A,B, two points.
- Optionally, var, a variable name.
equilateral_triangle(A,B ⟨,var ⟩) returns and draws the equilateral ABC, where AB to AC is counterclockwise.
With the argument var, C will be assigned to var.

equilateral_triangle(1/2+i/2,4+i)

equilateral_triangle(1/2+i/2,4+i,C)

evalc(affix(C))

−2

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+18

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