Ch 10 advances 3D visualisation to polyhedra (prisms and pyramids), Euler's formula, and the concept of mapping 3D objects to 2D views (front view, side view, top view).
A polyhedron is a 3D shape with flat polygonal faces. Prisms have two identical parallel bases connected by rectangles. Pyramids have one base with triangular faces meeting at an apex. A prism with triangular base has 5 faces; square base has 6 faces.
For any convex polyhedron: F + V − E = 2 (faces + vertices − edges = 2). Use this to find missing values or verify 3D shape properties.
A 3D object can be described by three 2D views: front view, side view, and top view. These projections help in technical drawing and understanding shape from different perspectives.
Download: https://ncert.nic.in/textbook/pdf/hemh110.pdf | Complete book: https://ncert.nic.in/textbook/pdf/hemh1ps.zip
Tetrahedron (4 triangles), cube (6 squares), octahedron (8 triangles), dodecahedron (12 pentagons), icosahedron (20 triangles). Each is a convex polyhedron with identical regular polygon faces.
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