Verify Euler’s formula for these solids.

(i) Number of faces = F = 7

Number of vertices = V = 10

Number of edges = E = 15

We have,

F + V - E = 7 + 10 - 15

= 17 - 15

= 2

Hence, Euler's formula is verified

(ii) Number of faces = F = 9

Number of vertices = V = 9

Number of edges = E = 16

F + V - E = 9 + 9 - 16

= 18 - 16

= 2

Hence, Euler's formula is verified