X, Y and Z coordinates
finding the midpoint of a line segment
- find the average of the two x-coordinates, then do the same for the y-coordinates
- these will be the coordinates of the midpoint
straight line graphs
horizontal and vertical lines: 'x = a' and 'y = a'
the main diagonals: 'y = x' and 'y = -x'
other sloping lines through the origin: 'y = ax' and 'y = -ax'
- a tells you the steepness of the line
- the bigger a is, the steeper the slope
- a minus sign tells you it slopes downhill
plotting straight line graphs
the tables of 3 values method
- choose 3 values of x and draw up a table
- work out the corresponding y vlaues
- plot the coordinates and draw the line
the x=0, y=0 method
- set x = 0 in the equation, and find y - this where it crosses the y axis
- set y = 0 in the equation and find x - this is where it crosses the x axis
- plot these two points and join them up with a straight…