NCERT Solutions Class 9 Maths Chapter 3 — Coordinate Geometry

Solution:

Step 1: The x-coordinate of a point refers to its horizontal position and is formally called the abscissa.

Step 2: The y-coordinate of a point refers to its vertical position and is formally called the ordinate.

Step 3: Therefore, the x-coordinate is the abscissa, and the y-coordinate is the ordinate.

Solution:

Step 1: The x-axis divides the plane into left (negative x) and right (positive x) halves.

Step 2: The y-axis divides the plane into upper (positive y) and lower (negative y) halves.

Step 3: The third quadrant is formed by the intersection of the negative x-axis and the negative y-axis.

Step 4: Therefore, any point in the third quadrant will have both its x-coordinate and y-coordinate as negative.

Solution:

Step 1: "3 units to the left of the y-axis" means the x-coordinate (abscissa) is -3.

Step 2: "4 units above the x-axis" means the y-coordinate (ordinate) is +4.

Step 3: Combining these, the coordinates of point P are (-3, 4).

Solution:

Step 1: For a point to lie on the x-axis, its y-coordinate must be 0 (e.g., (x, 0)).

Step 2: For a point to lie on the y-axis, its x-coordinate must be 0 (e.g., (0, y)).

Step 3: The given point M(0, -7) has an x-coordinate of 0 and a y-coordinate of -7.

Step 4: Therefore, point M(0, -7) lies on the y-axis, not the x-axis.

Solution:

Step 1: The point where the x-axis and y-axis intersect is called the origin.

Step 2: At the origin, there is no displacement along the x-axis (x=0) and no displacement along the y-axis (y=0).

Step 3: Therefore, the coordinates of the origin are (0, 0).