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Visualising Solid Shapes

Question
CBSEENMA8003309

What happens to F, V and E if some parts are sliced off from a solid? (To start with, you may take a plasticine cube, cut a corner off and investigate).

Solution
Consider the following cuboid ABCDEFGH:

Case I: The given cuboid has:
(i) Number of faces (F) = 6
(ii) Number of vertices(V) = 8
(iii) Number of edges (E) = 12
We have,                    F + V = 6 + 8 = 14
                        F + V - E = 14 - 12 = 2
i.e.                   F + V - E = 2
or the Euler's formula is verified.
Case II: [A part is sliced off]

We have:
         Number of faces (F) = 7
     Number of vertices (V) = 10
        Number of Edges (E) = 15
 Also,                                 F + V = 7 + 10 = 17
and                                F + V - E = 17 - 15 = 2
     Here also, Euler's formula holds true.