From a sheet of 20 m×10 m, 4 squares of side 2.5 m are cut out from the corners and made into a box.TSA of the box =
A square of side 2.5 m is cut off from all the corners. Therefore the length of a rectangular sheet changes to 15 m (20 - 2 × 2.5) and breadth to 5 m (10 - 2 × 2.5).
Therefore,
surface area of the resulting figure
= sum of areas of I, II, III, IV, V
= (15 × 2.5) + (5 × 2.5) + (15 × 2.5) + (5 × 2.5) + (15 × 5)
= 175 m2