Challenge Level

$OGH$ is an isosceles right-angled triangle:

Lines $AB$, $CD$, $EF$, and $GH$ are parallel.

- If lines $OC$ and $AB$ have the same length, calculate the area of trapezium $ABDC$.
- If lines $OE$ and $CD$ also have the same length, calculate the area of trapezium $CDFE$.
- If lines $OG$ and $EF$ also have the same length, calculate the area of trapezium $EFHG$.

Can you explain your results?