In the grid below, 2 sides of a trapezium PQRS have been drawn. Complete the drawing of trapezium PQRS where PQ is parallel to RS and RS is twice as long as PQ. Label dot S.

1. Determine the vector/direction and length of PQ

From Q to P, the segment moves in a specific direction on the isometric grid. Let the vector $\vec{QP}$ represent this movement.

2. Determine the position of S using the properties of the trapezium

Since $PQ$ is parallel to $RS$, the direction from R to S must be the opposite of Q to P (or same as P to Q depending on orientation, but to form a convex trapezium PQRS, $\vec{RS}$ is parallel to $\vec{QP}$). Given $RS = 2PQ$, the movement from R to S is exactly twice the movement from Q to P.
$\vec{RS} = 2\vec{QP}$.
Starting from R, move twice the grid distance of QP in the same direction to locate dot S.

3. Complete the trapezium

Draw the line segment RS. Then draw the line segment SP to close the trapezium PQRS. Label the new vertex as S.