1. These two pairs of lines form a parallelogram.
Functions and graphs
A3.3 Core Plenary
These two pairs of lines form a parallelogram.
If you are told the equations
of four straight lines, is there an easy way to see if they form a parallelogram?
Experiment with some
straight lines of your own.
What about other shapes?
Preamble
A fairly straightforward activity to recap the fact that gradient of a straight line is given by the coefficient of x (in an informal manner).
More capable pupils might be guided to ‘discover’ the rule that for two lines to cut at right angles (in order to make squares or rectangles) the product of the coefficients of x must be −1. (Using horizontal and vertical lines will probably cause difficulties at this point.)
The activity may be carried out with the whole class or in small groups followed by a whole-class discussion of results.
Possible content
Recognising and using the gradient of a straight line from the straight line formula.
Resources Square paper to draw straight lines, OHP with coordinate system on or another way of displaying graphs to the whole class.
Solution/Notes
Parallelograms have two pairs of parallel lines and pairs of parallel lines have the same gradient (the coefficient of x must be the same for each line).
Original Material © Cambridge University Press 2009
Original Material © Cambridge University Press 2009