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formulas

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Feynmann's Trick For Exponential Integrals

$$\int_0^{\infty} x^n e^{-tx} dx = \frac{n!}{t^{n+1}}$$

Finite and Infinite Geometric Sums

$$S_n = \frac{a(1-r^n)}{1-r}$$

Convolution

$$(f*g)(t)=\int_{-\infty}^{\infty} f(\tau)g(t-\tau)d\tau$$

Shockley Diode Model

$$I = I_S \cdot (e^{\frac{V_D}{nV_T}} - 1)$$

Schrodinger's Equation

$$\scriptsize i\hbar\frac{\partial}{\partial t}\Psi(x,t) = \left[-\frac{\hbar^2}{2m}\frac{\partial^2}{\partial x^2} + V(x,t)\right]\Psi(x,t)$$

L'Hopital's Rule

$$\lim_{x \to c} \frac{f(x)}{g(x)} = \lim_{x \to c} \frac{f'(x)}{g'(x)}$$

Lorentz Transformations

$$x' = \frac{x-vt}{\sqrt{1-v^2/c^2}}$$

Determinants of Matrices

$$\det(A)$$

Double Angle Trig Identities

$$\sin(2\theta) = 2 \cdot \sin(\theta) \cdot \cos(\theta)$$

Trig Angle Sum/Difference Identities

$$\scriptsize \sin(a \pm b) = \sin(a) \cos(b) \pm \cos(a) \sin(b)$$

Vector Projection

$$proj_{\vec{b}}(\vec{a})=\frac{\vec{a}\cdot\vec{b}}{\|\vec{b}\|^2}\vec{b}=(\vec{a}\cdot\hat{b})\hat{b}$$

Green's Theorem

$$\small \oint_C Pdx + Qdy = \iint_D \frac{\partial Q}{\partial x} - \frac{\partial P}{\partial y} dA$$

Hooke's Law (Modulus of Elasticity)

$$\frac{F}{A} = E\frac{\Delta L}{L}$$

Hooke's Law (Spring Constant)

$$F = -kx$$

Hyperbolic Functions

$$\sinh(x) = \frac{e^x - e^{-x}}{2}$$

Stokes' Theorem

$$\int_C \vec{F} \cdot d\vec{r} = \iint_S \nabla \times \vec{F} \cdot d\vec{S}$$

Cross Product

$$\vec{a} \times \vec{b} = \begin{vmatrix} \vec{i} & \vec{j} & \vec{k} \\ a_1 & a_2 & a_3 \\ b_1 & b_2 & b_3 \end{vmatrix}$$

Divergence Theorem

$$\iiint_V (\nabla \cdot \vec{F}) dV = \oiint_S (\vec{F} \cdot \hat{n}) dS$$

Dot Product

$$\vec{a} \cdot \vec{b} = \sum_{i=1}^n a_i b_i$$

Ampere's Law

$$\oint \vec{B} \cdot d\vec{l} = \mu_0 I$$

Gauss's Law

$$\oiint \vec{E} \cdot d\vec{A} = \frac{Q_{enc}}{\epsilon_0}$$

Cosine Law

$$c^2 = a^2 + b^2 - 2 \cdot a \cdot b \cdot \cos(\theta)$$

Definition of the Derivative

$$\frac{d}{dx}f(x) = \lim_{h\to 0}\frac{f(x+h)-f(x)}{h}$$

Pythagorean Trig Identities

$$\sin^2(x) + \cos^2(x) = 1$$

Cauchy's Integral Theorem

$$\oint_C f(z)dz = 0$$

Gravitational Potential Energy

$$U = mgh$$

Kinetic Energy

$$E_k = \frac{1}{2}mv^2$$

Laplace's Equation

$$\nabla^2 f = \nabla \cdot \nabla f = 0$$

Fundamental Theorem of Calculus

$$\int_a^b f(x) dx = F(b) - F(a)$$

Pythagorean Theorem

$$a^2 + b^2 = c^2$$