Defining the cotangent function. The cotangent function is an old mathematical function. It was mentioned in 1620 by E. Gunter who invented the notation of cotangens. Later on J. Keill (1726) and L. Euler (1748) used this function and its notation in their investigations.
A U.S. Department of Agriculture research scientist bred these beauties, and now they are grown by J. Berry Nursery in Texas. Five in series. The stunning black diamond crape myrtle has five different colors. We all know how different reds can be, and there is the Best Red, which is a very dark red. You might think it wouldn't show up with the dark burgundy leaves, but it is a beautiful mix of colors.
The Pink Velour Crepe Myrtle is a deciduous ornamental tree with bright pink blooms during summer and fall. New foliage comes out burgandy then turns dark green in color. Attractive bark in winter.