**Equation of straight lines :**

**1.General form **

**The first-degree equation in x and y is known as a general form of a straight line.**

**Example – ax + by + c = 0 , where a and b are not both zero at a same time.**

**x = 0 , Y-axis.**

**y = 0 , X-axis**

**x = a , parallel to Y-axis.**

**Y = b, parallel to X-axis.**

**The distance of a point (x, y ) from x-axis is |y| and from y-axis is |x|.**

**Slope = -a/b**

**Intercept on x-axis :**

** Put y=0.**

**x = -c/a**

**Intercept on y-axis:**

**Put x = 0**

**y = -c/b**

**2.Slope form**

**An equation of a line has slope m = tanθ and cutting off an intercept c on Y-axis.**

**Then**

**y = x.tanθ + c**

**y = mx+c**

### 3. Intercept form

**An equation of a straight line L and cutting of an intercepts a and b upon axes of X and Y respectively.**

**Then **

**x/a + y/b = 1**

**if the equation of a straight line L is –**

** a) parallel to X-axis, X-intercept is not defined.**

** b) parallel to Y-axis, Y-intercept is not defined.**