Coordinate geometry
Last updated: 16 Nov 2008
Every point in coordinate geometry is specified by two coordinates, an x coordinate which determines the horizontal position of the point and a y coordinate which determines the vertical position of the point.
The x-axis is measured from left to right (i.e. left is negative and right is positive) and the y-axis is measured from bottom to top.
For example the point ( 4, -2 ) is shown in the diagram below.
Equations of Lines
A line can be described by a linear equation in x and y the solutions of which form the points on a line. The standard form of the equation of a line is:
Where is the gradient (or slope) of the line and
is the y intercept i.e. where the line crosses the y-axis.
For example the line with the equation is plotted on the graph below.
You can see that the y intercept is -3 and that the gradient is 2 (i.e. the line rises by 2 each time you move 1 space left).
Contents
- Introduction
- Geometry tips
- Angles and lines
- Triangles
- The Pythagoras theorem
- Common triangles
- Common quadrilaterals
- The trapezium
- Circles, sectors and arcs
- Cuboids and cylinders
- Coordinate geometry
- Summary of geometry
Practice questions
Is this all that needs to be known for coordinate geometry? How about the distance formula? parabolas? transformations?
quote
The x-axis is measured from left to right (i.e. right is negative and left is positive)
unquote
I think you meant right is positive and left is negative.
I do indeed. I have corrected it on the page now.
Thank you for the correction.