# Linear equation

## Slope–intercept form of linear equation

$$y=mx+b$$

## Slope

$$m=tg\alpha $$

## Intercept form of linear equation

$$\frac{x}{a}+\frac{y}{b}=1$$

## General form of linear equation

$$Ax+By+C=0$$

## Normal Vector

$$\overrightarrow{n}(A,B)$$

## Direction Vector

$$\overrightarrow{v}(-B,A)$$

## Equation of a Line from 2 Points

$$\frac{y-{y}_{1}}{x-{x}_{1}}=\frac{{y}_{2}-{y}_{1}}{{x}_{2}-{x}_{1}}$$

## Angle between two lines

$${l}_{1}:y={m}_{1}\xb7x+{n}_{1}$$ $${l}_{2}:y={m}_{2}\xb7x+{n}_{2}$$

$$tg\phi =\left|\frac{{m}_{2}-{m}_{1}}{1+{m}_{1}\xb7{m}_{2}}\right|$$

Keywords: Linear equation