- Euler’s formula (Wikipedia)
Euler’s formula, named after Leonhard Euler, is a mathematical formula in complex analysis that establishes the fundamental relationship between the trigonometric functions and the complex exponential function. Euler’s formula states that, for any real number x, one has eix = cos x + i sin x, where e is the base of the natural logarithm, i is the imaginary unit, and cos and sin are the trigonometric functions cosine and sine respectively. This complex exponential function is sometimes denoted cis x (“cosine plus i sine”). The formula is still valid if x is a complex number, and is also called Euler’s formula in this more general case.
- Mid-Atlantic (United States) (Wikipedia)
The Mid-Atlantic is a region of the United States located in the overlap between the Northeastern and Southeastern states of the United States. The region typically includes five states, New York, New Jersey, Pennsylvania, Delaware, and Maryland, and the national capital of Washington, D.C.. Virginia and West Virginia are sometimes included in definitions of the region’s geography. The region has its origin in 18th century, and its states were each among the Thirteen Colonies of pre-revolutionary British America.