Right triangles in the plane: right_triangle

### 13.8.3 Right triangles in the plane: right_triangle

See Section 14.7.3 for right triangles in space.

The right_triangle command creates right triangles.

- right_triangle takes three mandatory arguments and one optional argument:
  - A,B, two points.
  - k, a nonzero real number.
  - Optionally var, a variable name.
- right_triangle(A,B,k ⟨var⟩) returns and draws the right triangle ABC, with the right angle at A and with length(AC)=|k|·length(AB). If k > 0, then AB to AC is counterclockwise; if k < 0 then AB to AC is clockwise.
  With the argument var, c will be assigned to var.

Examples.

- Input:
  right_triangle(i,-i,2)
  Output:
- Input:
  right_triangle(i,-i,-2)
  Output:
- Input:
  right_triangle(i, -i, 2, C)
  Output:
  Input:
  affix(C)
  Output:

  4 + i