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 common crepe myrtle (Lagerstroemia indica) was first brought to Charleston, South Carolina around 1790 from its natural home in China and Korea. It thrived in the warm climate there and has long been a symbol of summer in the South, with its vivid blooms.