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.
Most crepe myrtles in gardens are selections of L. indica or hybrids of that species with L. fauriei. The latter species has attracted much notice for its hardiness and exceptionally showy bark. Queenâs crepe myrtle, L. speciosa, grows only in the Tropical South. All crepe myrtles bloom on new wood and should be pruned in winter or early spring. On large shrubs and trees, remove basal suckers, twiggy growth, crossing branches, and branches growing toward the center of the plant.