This article is about Euler’s formula in complex analysis. For Euler’s formula in sin cos formulas pdf topology and polyhedral combinatorics, see Euler characteristic.

Euler’s formula is ubiquitous in mathematics, physics, and engineering. The physicist Richard Feynman called the equation “our jewel” and “the most remarkable formula in mathematics”. Bernoulli, however, did not evaluate the integral. Bernoulli did not fully understand complex logarithms.

Euler also suggested that the complex logarithms can have infinitely many values. Around 1740 Euler turned his attention to the exponential function instead of logarithms and obtained the formula used today that is named after him. It was published in 1748, obtained by comparing the series expansions of the exponential and trigonometric expressions. The view of complex numbers as points in the complex plane was described about 50 years later by Caspar Wessel. A point in the complex plane can be represented by a complex number written in cartesian coordinates. Euler’s formula provides a means of conversion between cartesian coordinates and polar coordinates.

Euler’s formula, implies several trigonometric identities, as well as de Moivre’s formula. Complex exponentials can simplify trigonometry, because they are easier to manipulate than their sinusoidal components. One technique is simply to convert sinusoids into equivalent expressions in terms of exponentials. After the manipulations, the simplified result is still real-valued. Another technique is to represent the sinusoids in terms of the real part of a complex expression and perform the manipulations on the complex expression. The reason for this is that the exponential function is the eigenfunction of the operation of differentiation.

In the four-dimensional space of quaternions, there is a sphere of imaginary units. The set of all versors forms a 3-sphere in the 4-space. In particular we may use either of the two following definitions, which are equivalent. Various proofs of the formula are possible. The rearrangement of terms is justified because each series is absolutely convergent. Another proof is based on the fact that all complex numbers can be expressed in polar coordinates. A Course in Complex Analysis in One Variable.

The Feynman Lectures on Physics, vol. Solution d’un problème concernant le calcul intégral, avec quelques abrégés par rapport à ce calcul” . Mémoires de l’Académie Royale des Sciences de Paris. A Modern Introduction to Differential Equations.

Euler’s Formula and Euler’s Identity : Rationale for Euler’s Formula and Euler’s Identity, video at Khanacademy. This page was last edited on 13 February 2018, at 21:10. For the similarity measure, see Cosine similarity. Basis of trigonometry: if two right triangles have equal acute angles, they are similar, so their side lengths are proportional. The most familiar trigonometric functions are the sine, cosine, and tangent. More precise definitions are detailed below.

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