Coordinates (Cambridge International IGCSE Maths)

2D Coordinates

What is the Cartesian plane?

• The Cartesian plane is a two-dimensional grid that has

  • a horizontal scale, called the x-axis
  • a vertical scale, called the y-axis

• The two axes meet at the origin

  • where x and y are both 0

What are coordinates?

• Coordinates are a pair of numbers, x and y, that describe the location of a point on the grid

  • They are written in brackets as ( x , y )

  • The point is

    • x units **on the horizontal scale
    • y units** on the vertical scale

• The origin is (0, 0)

  • Positive values of x *are to the right of the origin

    • Negative values are to the left

  • Positive values of y are above the origin

    • Negative values are below

• For example, from the origin:

  • (2, 5) is the point 2 units to the right and 5 units up
  • (-1, -4) is the point 1 unit to the **left **and 4 units down

• "Along the corridor, up the stairs" helps to remember** horizontal** then vertical,* ( x , y)

Exam Hint Check the scale on the coordinate grid! 1 square might not represent 1 unit.

Worked Example (a) Write down the coordinates of the point A shown on the axes below.

Answer:

A is 3 units to left, so x is −3 A is 4 units up, so y is 4 Give your answer in brackets

Final answer: (−3, 4)

(b) Mark the point B with coordinates (3,- 2) on the same set of axes.

Answer:

Start at the origin Count 3 units right and two units down Mark the point with a solid circle or cross and label it B