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.
Crepe Myrtles are among the toughest, most adaptable, and showiest plants that can be grown in the Texas landscape. Along with their bright colorful bloom display during the summer months the leaves of the Crepe Myrtle also turn orange, red and yellow in the fall.
The Catawba Crepe Myrtle is a great deciduous shrub or small tree. One of the best purple crepe myrtles. The tree has attractive bark in the winter. The Country Red Crepe Myrtle is a deciduous ornamental tree with bright pinkie-red flowers in summer and orange-yellow color in fall.