Triangle PQR is drawn on the Cartesian plane (each grid square is 1 unit). Find its area.

Class 9Coordinate GeometryCoordinate Geometry

Step-by-Step Solution

P (- 2, - 1)

and

Q (4, - 1)

lie on one horizontal line, so base

PQ = 6

. R

(1, 3)

3 - (- 1) = 4

units above it. Area

= \frac{1}{2} \times 6 \times 4 = 12

sq units.

Answer: D) 12 sq units

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.

Don't just memorise the answer — build a daily practice habit.