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.
A Myrtle for the Central Region. The quintessential Southern flowering tree has expanded its hardiness potential. Youâre not limited to Zones 7 â 9 to enjoy this gorgeous, pink, long-flowering tree. The Hopi Crape Myrtle has an increased cold tolerance level and will thrive up through Zone 6. Soft and crinkly, the pink flowers of Hopi Crape Myrtle are massed in large clusters for an astonishing visual impact.