Presentation onVISUALIZING SOLID SHAPES

By: Kaustubh SinghClass: - VIIIth A, Roll No: - 19

VISUALIZING SOLID SHAPES

Plane shapes have two measurements like length and breadth

and therefore they are called two-dimensional Shapes, whereas

a solid object has three measurements like length, breadth,

height or depth. Hence, they are called three-dimensional

shapes. Also, a solid object occupies some space.

lengthbreath

HEIGHT

length

breath

2D 3D

VISUALIZING SOLID SHAPES

TWO-DIMENSIONAL SHAPES

THREE -DIMENSIONAL SHAPES

1. Dimension - Dimension is a property of a shape, and tells us if the shape has depth. A school playground is 3-D, but a drawing you make on a flat piece of paper is 2-D.

2. Length - The edges of a shape have a certain length. The length of the edges of a shape is what gives it a certain size, and can be measured. The faces of both 2-D and 3-D shapes have edges of certain length. You experience this property when you measure the edge of something with a ruler.

3. Area - The amount of space the surface of one face takes up is called the area. If you put a shape on a piece of graph paper, the number of squares the face covers is the area. The area of a shape can be measured in square centimeters (cm2) and is a property of both 2-D and 3-D shapes. You have experience with this property when you notice that your friend got a bigger slice of pizza than you did.

FEW IMPORTANT TERMS

3. Surface Area - If you add together all of the areas from the faces of a 3-D shape, then the total is the surface area. It is the total amount of space needed to cover the outer surface of the shape. This is a property of 3-D shapes, and you might have noticed it when you've tried to figure out how much wrapping paper to use to wrap a present.

4. Volume - The amount of space that a 3-D shape takes up is called volume. Volume can either be filled with a solid (like the chocolate in a chocolate bar), a liquid (like the amount of milk in a glass), or a gas (like the amount of air in an empty box). Volume is a property of 3-D, but not 2-D, objects and can be measured in cubic centimeters (cm3) or in milliliters (mL). In fact, one cubic centimeter of water is also 1 milliliter of water! You experience volume when you help make cookies and measure out the ingredients with measuring cups

FEW IMPORTANT TERMS

1. The circle, the square, the rectangle, the quadrilateral and the triangle are examples of plane figures; the cube, the cuboid, the sphere, the cylinder, the cone and the pyramid are examples of solid shapes.

2. Plane figures are of two-dimensions (2-D) and the solid shapes are of three-dimensions (3-D).

3. The corners of a solid shape are called its vertices; the line segments of its skeleton are its edges; and its flat surfaces are its faces.

4. A net is a skeleton-outline of a solid that can be folded to make it. The same solid can have several types of nets.

5. Solid shapes can be drawn on a flat surface (like paper) realistically. We call this

6. 2-D representation of a 3-D solid.

SUMMARY

7. Two types of sketches of a solid are possible: An oblique sketch does not have proportional lengths. Still it conveys all

important aspects of the appearance of the solid. An isometric sketch is drawn on an isometric dot paper, a sample of which is

given at the end of this book. In an isometric sketch of the solid the measurements kept proportional.

8. Visualizing solid shapes is a very useful skill. You should be able to see ‘hidden’ parts of the solid shape.

9. Different sections of a solid can be viewed in many ways: One way is to view by cutting or slicing the shape, which would result in the cross-

section of the solid. Another way is by observing a 2-D shadow of a 3-D shape. 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.

SUMMARY