Co-ordinate Geometry — Class 9 Maharashtra SSC Mathematics revision notes
A 3-page visual revision sheet for Co-ordinate Geometry, written for Class 9 Maharashtra SSC Mathematics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDF
Co-ordinate Geometry in one look
naming a point by two numbers, the quadrants, and the lines parallel to the axes
Building the plane
- two perpendicular number lines are drawn, the horizontal X axis and the vertical Y axis
- they meet at the origin, the point O with co-ordinates (0, 0)
- a point is named by an ordered pair (x, y), and the order is what makes (3, 5) different from (5, 3)
- x is called the abscissa, measured from the Y axis, and y the ordinate, measured from the X axis
- each is carried with its sign, positive to the right and upward, negative to the left and downward
- the two axes together are called the co-ordinate axes, and the plane they set up is the Cartesian plane
Signs in the four quadrants
| Quadrant | x | y |
|---|---|---|
| First | + | + |
| Second | - | + |
| Third | - | - |
| Fourth | + | - |
Points on the axes themselves
- a point on the X axis has ordinate zero, so it looks like (a, 0)
- a point on the Y axis has abscissa zero, so it looks like (0, b)
- the origin (0, 0) lies on both axes at once
- a point on an axis belongs to no quadrant, since the quadrants are the open regions between the axes
- so the answer to which quadrant does (4, 0) lie in is none, it lies on the X axis
- these conditions are how a question turns lies on the Y axis into the equation x = 0
Plotting and reading points
- to plot (a, b), move a units along the X axis first, then b units parallel to the Y axis
- the order is fixed: across before up, and reversing it plots a different point
- choose a scale that fits every point on the page, and mark the same scale on both axes unless there is a reason not to
- label each plotted point with its name and co-ordinates
- to read a point off, drop perpendiculars to both axes and read the two values with their signs
- a rough plot is worth doing even when the question is purely algebraic, since it catches sign errors instantly
Page 1 of 3. The full sheet, all 3 pages, opens free in the app.
What this Co-ordinate Geometry sheet covers
- Cartesian system
- Origin
- Abscissa and ordinate
- Building the plane
- Signs in the four quadrants
- Points on the axes themselves
- Plotting and reading points
- Equation of a line parallel to an axis
- Lines parallel to the axes
- Identifying a figure from plotted points
- Distances that need no formula
- Turning conditions into equations
- Terms in this chapter
- Traps that cost marks
- Tricks that save time
How CapCompass uses this sheet
These notes are not a standalone PDF. CapCompass plans Mathematics chapter by chapter against your real exam dates and free hours, and when the plan reaches Co-ordinate Geometry the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.