EXERCISE 21

1.The adjoining net is made up of two equilateral triangles and three rectangles

(i) Name the solid it represents

(ii) How many faces,edges and vertices does this solid have ?

2.For each solid, count the numebr of faces , vertices and edges. Check if the Euler’s rule is true for each one.

(i)

(ii)

(iii)

(iv)

3.Name the solids that have

(i) 4 faces

(ii) 1 curved surface

(iii) 6 faces

(iv) 5 faces and 5 vertices

(v) 8 triangular faces

(vi) 6 rectangular faces and 2 hexagonal faces.

4.Name the different plane shapes needed to draw the net of a

(i) cube

(ii) triangular prism

(iii) triangular pyramids

5.Given here is the net of an octahedron with numbers 0 and 7 on the faces. Enlarge these on a cardboard to make a model.

(i) How many faces,edges and vertices does this solid have ?

(ii) Check whether Euler’s rule is true for the octahedron or not .

6.Draw the 2D representation of a

(i) cube

(ii) triangular prism

7.On an isometric dotted paper draw the following shapes.

(i) cube (ii) cuboid (iii) hexagonal prism (iv) pentagonal prism

8.Name the solid that would be formed by each net:

(i) fig

(ii) fig

(iii) fig