Basic form "Triangle"
The article shows how to make the basic form "Triangle"
Before folding, the square can be placed in a "window" when the lower and upper lines are horizontal (pass from left to right), and the right and left ones are vertical (go from top to bottom).
The square can also be placed with a "diamond" so that one of the corners is pointing down.
1. Arrange the square with a diamond. Raise the bottom corner, combining it with the top corner.
2. The resulting blank has the shape of an isosceles right-angled triangle.
When the figures are folded, the basic form"Triangle" can be placed in different ways. A habitual position is when the underside is the largest, that is, the base of an isosceles triangle. The triangle can also be located at a right angle down. This is not quite the usual position gave another name to this basic form - "kerchief".