Category : 3rd Class
Geometrical Shapes
OBJECTIVE
Geometric Shapes
A geometric shape is defined as a set of points or vertices and sides connecting to the point to form a closed entry. There are various kinds of geometrical shapes. Based upon the number of vertices and sides they are identified asfollows:
2D Geometric Shapes
Triangle 
· Triangle has three sides. · It has three vertices. 
Square 
· Squares have 4 equal sides and 4 right angles. · They have 4 lines of symmetry. · All squares belong to the rectangle family. · All squares belong to the rhombus family. · All squares are also parallelograms. 
Rectangle 
· Rectangles have 4 sides and 4 right angles. · They all have 2 lines of symmetry (4 lines if they are also a square) · All rectangles belong to the parallelogram family. 
Rhombus 
· Rhombuses (rhombii) have 4 equal sides. · Both pairs of opposite sides are parallel. · They all have 2 lines of symmetry (4 lines if they are a square) · All rhombuses belong to the parallelogram family. 
Parallelogram 
· Parallelograms have 2 pairs of parallel sides. · Some parallelograms have lines of symmetry (depending on whether they are also squares, rectangles or rhombuses), but most do not. 
Circle 
· Circles have a point in the centre from which each point on the diameter is equidistant. · They have infinite lines of symmetry. 
Ellipse 
· Ellipses are like circles which have been squashed or stretched. · They have 2 lines of symmetry. · They are also a special type of oval. · The longest and shortest diameters of the ellipses are called the major and minor axis. These axis are also the lines of symmetry. 
Crescent 
· Crescent shapes are made when two circles overlap, or when one circle is removed from another circle. · The perimeter of crescents made from two circular arcs. · They have one line of symmetry. · Our moon forms crescent shapes during its phases. 
Pentagon 
· 5 sided polygon 
Hexagon 
· 6 sided polygon 
Heptagon 
· 7 sided polygon 
Octagon 
· 8 sided polygon 
3D Geometric Shapes
Cube 
· Cubes have 6 faces, 12 edges and 8 vertices. · All sides on a cube are equal length. · All faces are square in shape. · A cube is a type of cuboid.

Cuboid 
· Cuboids have 6 faces, 12 edges and 8 vertices. · All the faces on a cuboid are rectangular.

Sphere 
· Spheres have either 0 or 1 faces, 0 edges and 0 vertices. 
Cylinder 
· Cylinders have either 2 or 3 faces, 0 or 2 edges, and 0 vertices. 
Cone 
· Cones have either 1 or 2 faces, 0 or 1 edge, and 1 apex (which is described by some mathematicians as a vertex). 
Regular Geometric shape
The geometric shapes whose all sides are equal sides and equal interior angles are known as regular geometric shape.
Irregular Geometric Shapes
The geometric shapes which have sides and angles of any length and size.
Example  1
Find the number of straight lines in the given figure.
(a) 8 (b) 9
(c) 10 (d) 11
Ans. (a)
Straight lines: AB, AC, BC, BE, CD, ED, AE and AD
So, number of straight lines = 8.
Example  2
Komal built a birdhouse at summer camp. What shape is the piece of wood that was cut out to make the door other birdhouse?
(a) Triangle (b) Diamond
(c) Circle (d) Pentagon
Ans. (c)
Circle shape is the piece of wood that was cut out to make the door of her birdhouse.
Example  3
The figure has ____ straight lines and ______ curves.
(a) 9, 10 (b) 14, 12
(c) 16, 8 (d) 15, 10
Ans. (c)
The figure has 16 straight lines and 8 curves.
Directions (Example 4  5): Look at the figure carefully and answer the questions based on it.
Example  4
How many more circles are there in the given figure than triangles?
(a) 15 (b) 16
(c) 17 (d) 18
Example  5
Number of sleeping lines in the figure is _______.
(a) 21 (b) 16
(c) 18 (d) 19
Ans. (Example 4  5)
Ans. 4. (c)
Explanation
Number of circles in joker's cap = 10
Number of circles in joker's hand =6+6 =12
Number of circles in joker's face = 3
Number of circles in  triangle APQR = 5
Total number of circles =30
Number of triangles in feet = 4
Number of triangles in hands = 2
Number of triangles in face = 1
Number of triangles in \[\Delta PQR=6\]
Total number of triangles = 13
There are \[3013=17\]more circles than triangles.
5. Ans. (a)
Explanation
Sleeping lines in jokes cap = 2
Sleeping lines in face = 2
Sleeping lines in neck =1
Sleeping lines in hands =4
Sleeping lines in \[\Delta PQR=6\]
Sleeping lines in legs =6
Total number of sleeping lines =21
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