How many points in the plane have their ordinate equal to 0?

Class 9Coordinate GeometryCoordinate Geometry

Step-by-Step Solution

Ordinate 0 means the point lies on the

x

-axis, and the

x

-axis contains infinitely many points such as (1, 0), (−2, 0) and (7.5, 0). Only the abscissa is left free to change.

Answer: B) Infinitely many

Two perpendicular axes — horizontal

(x

-axis) and vertical

(y

-axis) — meet at the **origin** (0, 0). Together they divide the plane into four **quadrants**:

- **I**:

x > 0, y

> 0 (top right)
- **II**:

x < 0, y

> 0 (top left)
- **III**:

x < 0, y

< 0 (bottom left)
- **IV**:

x > 0, y

< 0 (bottom right)

Points ON the axes don't belong to any quadrant. (a, 0) sits on the

x

-axis; (0, b) sits on the

y

-axis.

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