Let \(A(3,-4)\), \(B(9,-4)\), \(C(5,-7)\) and \(D(7,-7)\). Show that \(ABCD\) is a trapezium.
Proof:
The slope of \(AB\) \(=\)
The slope of \(CD\) \(=\)
The slope of \(BC\) \(=\)
The slope of \(AD\) \(=\)
The slopes of \(AB\) and \(CD\) are , so the lines are .
Similarly, the slopes of \(BC\) and \(AD\) are , so the lines are .
Therefore, \(ABCD\) is a trapezium.
Hence, verified.