Plotting Points in the Coordinate Plane

• Plot points given ordered pairs accurately on graph paper.
• Identify collinear points lying on the same straight line.
• Find mirror images across x-axis, y-axis, and origin.
• Describe shapes formed by joining plotted vertices (square, rectangle, triangle).
• Solve NCERT Ex. 3.2 on reading and plotting coordinates.

1. Plotting steps — Start at origin; move |x| units left/right, then |y| up/down.
2. Negative moves — x = −4: move 4 left; y = −3: move 3 down.
3. Reflection in x-axis — (x, y) → (x, −y).
4. Reflection in y-axis — (x, y) → (−x, y).
5. Reflection in origin — (x, y) → (−x, −y).
6. Collinearity — Three points on same line (e.g. all have y = 2).
7. Vertices of polygon — Join (1,1), (5,1), (5,4), (1,4) → rectangle.
8. Midpoint (intro) — Average of x and y coordinates (Class 9 extension).
9. NCERT — Plot A(1, 9), B(2, 8), … check if collinear.
10. Scale — Choose equal unit scale on both axes unless problem specifies otherwise.

NCERT: Mirror image of (3, −4) in the x-axis

Reflection in x-axis changes sign of y:
(3, −4) → (3, 4)
Check: original 4 units below x-axis; image 4 units above
Reflection in y-axis would give (−3, −4)
Reflection in origin would give (−3, 4)

• Moving y units horizontally (x comes first in (x, y)).
• Unequal scales on axes distort shape without noticing.
• Forgetting negative direction for negative coordinates.
• Labeling point name away from dot causing confusion.
• Assuming collinear without checking slope or alignment.

• Plot (−2, 5) — describe moves from origin.
• Image of (−1, 6) in y-axis?
• Are (0, 0), (2, 2), (4, 4) collinear?
• Vertices (0,0), (3,0), (3,3), (0,3) form which shape?
• Image of (2, −3) in origin?

Open the Practice tab for graded questions on Plotting Points in the Coordinate Plane.