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.
Crepe Myrtle Trees: Colorful Ornamental Trees Increase Property Value. Landscapers and homeowners choose to plant Crepe Myrtle when a splash of color is needed. These small to medium sized trees provide glamorous colors from late spring to late summer. Best planted in the warmer locations of the United States, Crepe Myrtles prefer USDA Hardiness Zones 6 to 10.