Dear Sir,
Since the length and height remains same (red and blue) and over all triangle that means angle remains same in both fig. a and b that means slope is also same in both case when slope and angle is same how can the area covered by red n blue box differ as there surface area is also same in both fig. which is true for yellow n green box also that means surface are will be equal for red n blue n green n yellow in both fig. in such case boxes are placed in the most optimum place to cover the area in fig a and non optimum in fig b.
Regards,
Neha Verma