Class 7 · Chapter 15
Visualising Solid Shapes
3D shapes; faces, edges, vertices; nets; oblique and isometric sketches; Euler's formula.
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Detailed theory
2-D shapes have length and breadth (circle, square, triangle). 3-D solids also have height (cube, cylinder, sphere). Solids have faces, edges, vertices.
Key concepts & formulas
01
A polyhedron is a solid whose faces are polygons.
02
Cube: faces, edges, vertices.
03
Sphere: no vertices or edges; curved surface.
04
Cylinder: circular flat faces, curved surface.
05
Euler's formula: (for convex polyhedra).