Maths for Class 9
FAQs on NCERT Class 9 Maths Coordinate Geometry
1. What are the key topics in Class 9 Coordinate Geometry that I should focus on for my exams?
For the CBSE 2025-26 exams, focus on these core areas in Coordinate Geometry:
- The structure of the Cartesian plane (x-axis, y-axis, origin, and quadrants).
- Identifying the abscissa (x-coordinate) and ordinate (y-coordinate) of a point.
- Plotting points with given coordinates accurately in the correct quadrant.
- Recognising the coordinates of points that lie on the x-axis or y-axis.
- Understanding the sign conventions (+/-) for coordinates in each of the four quadrants.
2. What types of 1-mark questions are frequently asked from Chapter 3, Coordinate Geometry?
Typically, 1-mark questions are objective or very short answer types. Expect questions like:
- In which quadrant does the point (-3, 7) lie?
- What is the abscissa of the point (5, -2)?
- A point lies on the y-axis at a distance of 4 units from the origin in the positive direction. What are its coordinates?
- What is the perpendicular distance of the point (4, 6) from the x-axis?
3. How do I answer a question asking to plot a point, for instance, P(-2, 4), to get full marks?
To ensure you get full marks for plotting a point like P(-2, 4), follow these steps:
- Draw the x-axis and y-axis on graph paper and label them clearly (X, X', Y, Y'). Mark the origin (0,0).
- Start at the origin. Since the abscissa (x-coordinate) is -2, move 2 units along the negative x-axis.
- From that position, since the ordinate (y-coordinate) is +4, move 4 units up, parallel to the positive y-axis.
- Mark the final position clearly with a dot and label it as P(-2, 4).
4. From an exam perspective, what is the importance of understanding quadrants and the signs of coordinates?
Understanding quadrants and sign conventions is crucial because it helps you quickly verify your answers and avoid common errors. For any given point (x, y):
- Quadrant I: Both x and y are positive (+, +).
- Quadrant II: x is negative, y is positive (-, +).
- Quadrant III: Both x and y are negative (-, -).
- Quadrant IV: x is positive, y is negative (+, -).
5. What are some expected 2 or 3-mark questions from this chapter?
For 2 or 3 marks, questions usually require you to plot multiple points and identify the resulting figure. For the 2025-26 session, you can expect questions like:
- Plot the points A(1, 1), B(4, 1), C(4, 4), and D(1, 4). Join them in order and identify the geometric shape formed.
- Given a graph with plotted points, write down the coordinates of three different points shown.
- Plot the points P(-3, 0), Q(5, 0), and R(0, 4). Identify the type of triangle formed by joining these points.
6. What is the difference between the abscissa and the ordinate, and why is this distinction crucial for plotting points?
The terms abscissa and ordinate refer to the two parts of a coordinate pair (x, y).
- The abscissa is the x-coordinate. It represents the perpendicular distance of a point from the y-axis.
- The ordinate is the y-coordinate. It represents the perpendicular distance of a point from the x-axis.
7. How does the concept of a point lying on an axis form the basis for important questions?
This concept is frequently used in exam questions to test fundamental understanding. The key rules are:
- If a point lies on the x-axis, its y-coordinate (ordinate) must be zero. Its coordinates will be of the form (x, 0).
- If a point lies on the y-axis, its x-coordinate (abscissa) must be zero. Its coordinates will be of the form (0, y).
8. Are there any Higher Order Thinking Skills (HOTS) questions that can be asked from this chapter?
Yes, even from an introductory chapter like Coordinate Geometry, HOTS questions can be framed to test application and logical reasoning. Examples include:
- Find the coordinates of the mirror image of the point (-3, -5) with respect to the x-axis.
- Plot three vertices of a rectangle, A(1, 2), B(5, 2), and C(5, 6). Find the coordinates of the fourth vertex, D, to complete the rectangle.
- A point is in the fourth quadrant. If its perpendicular distances from the x-axis and y-axis are 4 and 3 units respectively, what are its coordinates? (Answer: (3, -4)).
9. Can a point lie on both the x-axis and y-axis simultaneously? Explain why this is an important concept.
Yes, a point can lie on both axes simultaneously. This special point is the origin. A point on the x-axis has a y-coordinate of 0, and a point on the y-axis has an x-coordinate of 0. The only point that satisfies both conditions is (0, 0). Understanding this is key because the origin is the fundamental reference point from which all other positions on the Cartesian plane are measured.
