44.What is the least number of planes that can enclose a solid? Name the simplest regular polyhedron and verify Euler’s formula for it.
At least 4 planes can form to enclose a solid. Tetrahedron is the simple polyhedron. Following figure represents a simplest solid, called tetrahedron.
A tetrahedron has: 4 triangular faces, i.e. F = 4 4 vertices, i.e. V = 4 6 edges, i.e. E = 6 Now, substituting the values of F, V and E in Euler's formula, i.e. F + V = E + 2 we have 4 + 4 = 6 + 2 8 = 8, which is true. Thus, Euler's formula is verified for a tetrahedron.
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45.Name the figure shown here. (i) How many faces does it have? (ii) How many vertices does it have? (iii) How many edges does it have?
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46.
Write the number of (i) faces (ii) edges (iii) vertices for a triangular prism.
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47.Number of faces of a pyramid is 5. Find the number of its vertices when its edges are 8.
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48.What is Euler’s formula? Using Euler’s formula, find the number of faces of tetrahedron having vertices as 4 and 6 edges.
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49.What is a triangular pyramid? What is a pyramid called if its base is a square?
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50.A dice is a cube in which the number on the opposite faces must total 7. Draw its net.