Straight lines what you should know- Flashcards
What is the gradient of a horizontal line?
m=0
What is the equation of a horizontal line
y=b
Equation of the x axis?
y=0
Gradient of a vertical line
m is undefined
Equation of a vertical line
x=a
Equation of y axis
x=0
Gradient formula
y2-y1/x2-x1
How to find equation of a straight line?
Have a point on the line and the gradient of said line and put in the equation y-b =m(x-a)
How to find gradient of straight line when equation is known?
Rearrange formula y=mx+c
How to find size of the angle between a straight line and the x axis
Use equation m=tanØ
Rule for parallel lines
m1=m2
Rule for perpendicular lines
m x m perpendicular = -1
How to find point of intersection between two straight lines
Use simultaneous equations between the two equations or use y=y and solve
What does it mean if three points are collinear
They lie in a straight line
How do you show points A,B and C are collinear
Show that mAB = mBC and since B is a common points they are said to be collinear.
