Construct a trapezium ABCD such that AB is parallel to DC, AB = 10 cm, AD = 8 cm, DC = 4 cm, and angle ADC = 90 degrees.

To do this, you can use a set square or a compass and ruler. Place one edge of a set square along AQ, then slide it along a ruler until the other edge passes through D. Draw a line along this edge through D. This line will contain the side DC.

Measure 4 cm from point D along the parallel line. Mark this point as C. (Assume C is to the right of D, consistent with the general orientation of the figure).

Since angle DCB = 90°, the line segment CB must be perpendicular to DC. As DC is parallel to AQ, CB will also be perpendicular to AQ. Draw a line from C that is perpendicular to the line containing DC and extends towards AQ.

The point where the perpendicular line from C intersects line AQ is point B.

Connect points A to B, B to C, C to D, and D to A to form the trapezium ABCD.