CBSE Class 8 Annual Assessment

Chapter 4: Exploring Some Geometric Themes

Summary

This chapter explores two geometric themes: fractals and the visualisation of solids. Fractals are self-similar shapes that repeat the same pattern at smaller and smaller scales, seen in ferns, coastlines and lightning. The Sierpinski Carpet removes the central square of a \(3\times3\) grid repeatedly, so the remaining squares follow \(R_n = 8^n\); the Sierpinski Triangle removes the middle of four triangles; and the Koch Snowflake replaces each side with a bump, growing the perimeter without bound. Fractals appear in temple architecture and African textiles. The second theme is representing solids on a plane. Prisms and pyramids are named by their base shapes, with set counts of faces, edges and vertices. A net is a solid unfolded flat; a cube has \(11\) distinct nets, a regular tetrahedron has \(2\). Nets also solve shortest-path problems on a cuboid. Projections give the front, top and side views of a solid, and an isometric projection — where all edges project to equal lengths — is drawn on an isometric grid to convey three-dimensional shape clearly.

Key terms

Important questions

Explore interactively

Practice quiz