The two latches make known the fact that this is an isosceles triangle. Here, x is the base angle. There are two base angles in isosceles triangles. Base angles have the same measure. This explains the reason for 2x in the equation below.
In the function the .72 means that each unit of time 72% of the value is retained. This means that 28% percent of the value is lost or decays because 1-0.72=0.28 or 28 percent.
