CONCEPT OF STRAIGHT LINE OF CLASS-11

All Formulas of Coordinate Geometry.
Coordinate of  origin	O (0,0)
Equation of x-axis	y = 0
Equation of y-axis	x = 0
Equation parallel to x-axis	y = ± k
Equation parallel to y-axis	x = ± k
The slope of a Line Using Coordinates	m = Δy/Δx     = (y2 − y1)/(x2 − x1)
The slope of a Line Using General Equation Ax + By + c = 0	m =  - { A / B }
The slope of a Line using angle (θ)	m = tanθ
For parallel Lines	m1 = m2
For Perpendicular Lines,	m1.m2 = -1
General Form of a Line	Ax + By + C = 0
Slope , Intercept of  y-axis Form of a Line	y = mx + c
Slope , Intercept of  x-axis Form of a Line	y = m(x - d )

Intercept-Intercept Form	x/a + y/b = 1
Perpendicular from	x cos α + y sin α = a
Point-Slope Form	y − y1= m(x − x1)
If two points are given	y − y1=[ (y2 − y1)/(x2 − x1) ]  (x − x1)
Midpoint Formula	M (x, y) = [(x1 + x2) /2, (y1 + y2) /2 ]
Angle Formula	tan θ = [(m1 – m2)/ 1 + m1m2]
Area of a Triangle Formula	1/2[|x1(y2−y3)+x2(y3–y1)+x3(y1–y2)| ]
Distance from a Point to a Line	d = [|Ax1 + By1 + C| / √(A2 + B2)]

Distance from origin to a Line	d = [| C| / √(A2 + B2)]
Section Formula (Internal division)	P(x, y) = [(m1x2 + m2x1)/(m1 + m2), (m1y2 + m2y1)/(m1 + m2)]
Section Formula (External division)	P(x, y) = [(m1x2 – m2x1)/(m1 – m2), (m1y2 – m2y1)/(m1 – m2)]