Download Co- Ordinates

Year 8 Mathematics
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Co-Ordinates
Learning Intentions
• Pupils should be able to
• use and plot co-ordinates in all 4 quadrants
• use negative numbers in context
• find the mid- point of a line
• Solve problem using co-ordinates
Co-Ordinate Systems
• Used to specify a location
• Latitude and Longitude
• Ordinance Survey 6 figure Grid system
• Post Codes
• GPS
• Cartesian Co-ordinates
Cartesian Co-ordinates
• Devised by René Descartes
(1596-1650)
• Two axes at right angles
• Y-axis is vertical
• X-axis is horizontal
• The point (0, 0) is called the
Origin.
• Y’s Up and X is across
X and Y Co-ordinates
• Co-ordinates are written as two numbers in
brackets separated by a comma.
• For example (2, 4) and (8, 7)
• The first number refers to the x-ordinate
• The second number refers to the y-ordinate
• Together they are called co-ordinates
Plotting Co-ordinates
• When plotting co-ordinates we
always start from the origin
• To plot the point (2, 3) we start at
the origin and move two squares in
the x (horizontal) direction and
then three square in the
y (vertical) direction.
• To plot the point (8, 9) we start at
the origin and move eight squares
in the x (horizontal) direction and
then nine square in the
y (vertical) direction.
Mid-Point
• The mid-point of a line is the point in the middle of
the line
• You can find the co-ordinates of the mid-point by
finding the average of the x ordinates at each end
of the line and the y ordinates at each end of the
line.
Finding the mid-point
• Find the mid-point of the line from
(2, 4) to (6, 2)
26
• x ordinate = 2 = 4
• y ordinate =
4 2
2
• Co-ordinates of
• mid-point = (4, 3)
=3
Horizontal Lines
• For a horizontal line, all the points on the line have
the same y ordinate.
Vertical Lines
• For a vertical line, all the points have the same x
ordinate
Properties of Shapes
• Quadrilateral
• Four sides
• Trapezium
• Four sides
• One pair of parallel sides
• Parallelogram
• Four sides
• Two pairs of parallel sides
• Opposite sides equal
Properties of Shapes
• Rhombus
• Four sides
• Opposite sides parallel
• All sides equal
• Rectangle
• Four sides
• Opposite sides parallel
• Four right angles
Properties of Shapes
• Square
•
•
•
•
Four sides
Opposite sides parallel
Opposite sides equal
Four right angles
• Kite
• Four sides
• Adjacent sides equal
The Four Quadrants
• Extending the x and y axes beyond the
origin gives the negative scales.
• The areas of the graph between axes
are called quadrants. So now we have
four quadrants in total.
• Co-ordinates in these quadrants are
still described in terms of x and y. But
now we can have negative values for
x, y or both.
• For example in the below:
• The coordinates of A are (-2, 3).
• The coordinates of B are (-3, -4).
Alien Attack
• How many Aliens can you kill!
http://www.flashymaths.co.uk/swf/alien.swf