The Free Triangle tool allows you to construct a triangle by precisely placing its three vertices. The initial touch defines the first vertex. While keeping your finger on the screen, drag it to another location and press the Mark Button.
This defines the second vertex of the triangle. The last vertex is set where you lift your finger from the Paper. You can restrict the construction of the vertices using the Drag Constraint button (move freely, move horizontally, move vertically). One other construction option you can use is the Bezier Points button. It looks like this
and controls how many Bezier Points are created for each side. See the
Move Bezier Point tool for how to use these invisible points. Here’s an example of free triangle construction.