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 tree is basically all right and will bloom next season. Always prune before growth starts in the spring. Foliage Curls, Turns Yellow shows Aphids. Check crape myrtle stems and leaves for bunches of soft-bodied, pear-shaped, insects a little bigger than the head of a pin. They may be white, yellow, red or brown.