Euler's formula

Etymology
.

Proper noun

 * 1)  Formula which links complex exponentiation with trigonometric functions:
 * $$ e^{i \theta} = \cos \theta + i \sin \theta $$
 * 1)  Formula which calculates the normal curvature of an arbitrary direction in the tangent plane in terms of the principal curvatures $$\kappa_1$$ and $$\kappa_2$$ and the angle $$\theta$$ which that direction makes with the first principal direction:
 * $$ \kappa_n(\theta) = \kappa_1 \cos^2 \theta + \kappa_2 \sin^2 \theta $$

Translations

 * Afrikaans: Euler se formule
 * Arabic: صِيغَة أُويْلِر
 * Bulgarian: формула на Ойлер
 * Catalan: fórmula d'Euler
 * Chinese:
 * Mandarin: 歐拉公式
 * Czech: Eulerův vzorec
 * Danish: Eulers formel
 * Dutch: formule van Euler
 * Esperanto: Eŭlera formulo
 * Estonian: Euleri valem
 * Finnish: Eulerin lause
 * French: formule d'Euler
 * German: eulersche Formel
 * Hebrew: נוסחת אוילר
 * Hindi: यूलर का सूत्र
 * Icelandic: jafna Eulers
 * Indonesian: rumus Euler
 * Italian: formula di Eulero
 * Japanese: オイラーの公式
 * Khmer: រូបមន្តអយល័រ
 * Korean: 오일러의 공식
 * Lithuanian: Oilerio formulė
 * Norwegian: Eulers formel
 * Persian: فرمول اولر
 * Polish: wzór Eulera
 * Portuguese: fórmula de Euler
 * Romanian: formula lui Euler
 * Russian: фо́рмула Эйлера, фо́рмула Эйлера
 * Serbo-Croatian:
 * Cyrillic: Еулерова формула, Ојлерова формула
 * Roman: Eulerova formula, Ojlerova formula
 * Slovene: Eulerjeva formula
 * Spanish: fórmula de Euler
 * Swedish: Eulers formel
 * Thai: สูตรของออยเลอร์
 * Welsh: fformwla Euler