To

1
Introduction
To Coordinates
2
Rectangular Coordinate Plane

• A French mathematician
• Rene Descartes
• He used a pair of numbers to indicate
• the position of a point on a plane.

3
y
Y - axis
( x , y )
P
x
The vertical number line is called the y-axis.
Any point P on the plane is described by two
numbers x and y called coordinates.
y
x
o
origin
X - axis
The horizontal number line is called the x-axis.
The point of intersection of the axes is called
the origin O.
4
Example 1
B
( -4, 4 )
C
A
( 3, 1 )
( -3, 0 )
C
Which point lies on the x-axis?
Write down the coordinates of the points marked
A, B and C.
5
Example 2
Plot the points P( -3, 1) and Q( 4, -2).
P
Q
6
Example 2
Which point lies on the x-axis?
A
( 2, 3 )
D
C
( -1, 2 )
P
D
( 1, 0 )
Q
B
( -3, -2 )
Write down the coordinates of the points marked
A, B,C and D.
7
Equation
of a
Straight line
8
(No Transcript)
9
(-3,4)
(2,4)
(4,4)
What is the coordinate of A?
What is the coordinate of B?
What is the coordinate of C?
10
4
4
4
(-3,4)
(2,4)
(4,4)
What are the y-coordinates of three points?
11
What is the equation of the line?
12
L1
y4
13
X2
Would you deduce the equation of L4?
y1
Using the same method, find the equation of L2?
How about the equation of L3?
x-coordinates of four points on the line are all
2, thus the equation of the line is x2
y-3
14
Acknowledgement
Wong Kat Yiu Leung Kin Keung Lau Sai On
17/3/98