RD Sharma Solutions for Class 7 Chapter 19 “Visualising Solid Shapes”- Plane figures or shapes have two measurements, namely length and breadth. Hence, they are called two-dimensional shapes, whereas a solid object has three measurements, namely length, breadth, height or depth. Hence, they are called three-dimensional shapes. Also, a solid shape occupies some space. In this chapter, we will learn about one-dimensional shapes, two-dimensional shapes and three-dimensional shapes. In this chapter, students concentrate on faces, vertices and edges of a three-dimensional figure such as cuboid, cube, prism, pyramid, cone and so on. It also explains “Euler’s relation for three-dimensional figures” very well through examples. It gives an account on nets for 3D – shapes.