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.
Crape Myrtle. The crape myrtle (Lagerstroemia indica) is a summer-blooming deciduous tree that grows in USDA zones 7 through 9. Crape myrtles have several flower colors, with cultivars such as Catawba and Purple Tower having purple blooms. The trees grow up to 30 feet tall with a domed canopy. Plant crape myrtles in full sun.