The yellow triangle is divided by the 2m stick in two triangles.
The base of each triangle measures 2m – the length of the stick.
To determine the area of a triangle, we have to calculate: height
× base/2. In order to measure the area of those two triangles, we
have: height × 2/2. But it is clear that 2/2=1, so the area of these
triangles equals their height