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.
Seeing a crepe myrtle in its full summer splendor sends some of us running to the garden shop to buy a plant the same color. But don't buy impulsively. Pay attention to the plant's tag. Make sure that it is not only the exact color that you want, but also the right size and look you hope to achieve.