CBSE / NCERT Solutions Class 8 Maths – Chapter 16 – Visualizing Shapes
The topic – Visualizing shapes from Class 8th Maths discussed here. We have discussed in earlier blogs that various types of figures exist like one-dimensional, multi-dimensional like two dimensional and three-dimensional figures. We come across many of them in our day to day life.
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A figure having the only length like a line segment is known as one dimensional
A figure having only length and breadth like a polygon is known as two dimensional
A figure having length, height and breadth like a cuboid is known as three dimensional
Visualization of 2-D shapes and their representation on paper is very convenient. We will now understand how to visualize 3-D shapes.
A three-dimensional solid shape composed of polygons is called a polyhedron. We will understand the words related to polyhedron-
Faces:-The polygons forming a polyhedron are called its face.
Edges:-The line segments where the faces of a polyhedron intersect are called its edges.
Vertices:-The corners where the edges of a polyhedron intersect are called its vertices.the point, where three or more edges meet, is called a vertex.
Examples of polyhedron
- Cuboid – A cuboid has 6 faces,8 vertex, and 12 edges
- Cube – A cuboid has 6 faces,8 vertex, and 12 edges
- Square pyramid-A square pyramid has 5 faces ,8 edges, and 5 vertices
- Triangular Pyramid-A triangular pyramid has 4 face, 6 edges, and 4 vertex.
- Triangular prism-A triangular prism has 5 faces, 9 edges, and 6 vertices.
We come across many of the shapes that are actually not polyhedron but they are made up of polygons.eg:- a sphere, a cone, a cylinder.
Watch and understand 2D -3D shapes with 2D-3D animated videos, for demo click 8th Class Maths
Regular polyhedron:-If the faces of a polyhedron are made up of regular polygons and the same number of faces meets at each vertex, a polyhedron is called a regular polyhedron. Eg:-Cube
A cuboid is not a regular polyhedron since its faces are not congruent rectangles.
Convex polyhedron:-if in any polyhedron the line segment joining any two points on its surface lie entirely inside or on the polyhedron, a polyhedron is called a convex polyhedron, in other cases, it is a concave polyhedron. Cube, cuboid, pyramid, and prism are examples of convex polyhedrons.
In the next article, we will try to understand prism and the various types of the prism. Also, we will understand pyramid and platonic solids.