Class 7 Maths Visualising Solid Shapes Viewing Different Sections Of a Solid

Viewing Different Sections Of a Solid

Visualizing solid shapes is a very useful skill. We can see the hidden parts of the solid shape. Different

sections of a solid can be viewed in many ways:

(a) One way is to view by cutting or slicing the shape, which would result in the cross-section of the solid as shown in the given figure.

            Class_7_Visualising_Solid_Shapes_Cross_Section_Of_Solid                                                     

(b) Another way is by observing a 2-D shadow of a 3-D shape.

        Class_7_Visualising_Solid_Shapes_Observing_2DShadow_Of_3DShape                         

Here, a circular plate is placed when the Sun at the noon time i.e. just right above the plate as shown in the given figure. The position of the shadow of the plate is changes with respect to Sun.

(c) A third way is to look at the shape from different angles; the front-view, the side-view and the top- view can provide a lot of information about the shape observed.

    Class_7_Visualising_Solid_Shapes_Observing_2DShadow_Of_3DShape1       

 

One can look at an object standing in front of it or by the side of it or from above. Each time one will get a different view. Here is another example of one can gets different views of a given building.

Problem: Here are the shadows of some 3-D objects, when seen under the lamp of the overhead projector. Identify the solid (s) that match each shadow.

Class_7_Visualising_Solid_Shapes_DifferentShapes1

Solution:

           Class_7_Visualising_Solid_Shapes_Different_3D_Shapes_2               

Problem: Examine if the following are true statements:

(i) The cube can cast a shadow in the shape of a rectangle.

(ii) The cube can cast a shadow in the shape of a hexagon.

Solution:

(i) True

The cube can cast a shadow in the shape of a rectangle.

 Class_7_Visualising_Solid_Shapes_Shadow_Of_Cube

                                                        

(ii) False

A cube can cast a shadow in the shape of a rectangle.

 Class_7_Visualising_Solid_Shapes_Shadow_Of_Cube

                                                        

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