LEARNING OBJECTIVES
This lesson will help you to –
- Identify and recognise different plane figures or 2-D shapes like triangle, quadrilateral, rectangle, square and circle and their properties.
- Identify and recognise different solid shapes or 3-D shapes like cone, cube, cuboid, cylinder, sphere and their properties.
- Identify edges, corners or vertices and faces in the given shape.
- Understand the basic concept of geometry.
- Learn about point, line, line segments and rays.
A rectangle, a square, a triangle, circle or oval are plane or 2-dimensional (2-D) figure or shapes.
Rectangle | ABCD is a rectangle. It has 4 sides : AB, BC, CD, DA It has 4 corners: A, B, C, D Opposite sides of rectangle are equal: Side AB = CD Side BC = AD |
Square | ABCD is a square. It has 4 sides : AB, BC, CD, DA It has 4 corners: A, B, C, D All sides of square are equal: AB = BC = CD = AD Since the opposite sides of a square are equal, it is also a rectangle. But rectangle is not a square. |
Triangle | ABC is a triangle. It has 3 sides : AB, BC, CA It has 3 corners: A, B, C |
Circle | This is a circle It has 1 curved side. It has 0 corners or no corners. |
Oval | This is an oval It has 1 curved side. It has 0 corners or no corners. |
3-dimensional shapes (3-D shapes) or Solid Shapes
A cuboid, cube, cylinder, sphere and cone are 3 -D shapes
Solid shapes have faces, edges and corners(vertices).
The outside of a solid shape is called its face or surface. Solid shapes have flat or curved faces.
An edge is where two faces meet.
These shapes are solid or hollow.
They have three dimensions – length, width and height.
Cube  | A Cube has flat faces. There is no curved face. All the sides of cube are equal. A cube has total 6 faces and all faces are of square. A cube has 12 edges and 8 corners or vertices. |
Cuboid | A Cuboid has flat faces. There is no curved face. All the sides of cuboid are not equal. Each face is a rectangle. A cuboid has total 6 faces. A cuboid has 12 edges and 8 corners or vertices. |
Cylinder  | A cylinder has 3 faces. Cylinder has 2 flat faces and 1 curved face. Cylinder has 2 curved edges. Cylinder has no corner. |
Cone | A cone has a total of 2 faces. Cone has 1 flat faces and 1 curved face. Cone has 1 curved edge. Cone has 1 vertex or corner. |
Sphere | Sphere has one curved surface. Sphere has no vertex or corner or edge. |
Simple Concepts in Geometry
Point | A small dot made with the sharp pencil gives your point. We use a capital letter to name a point. A point shows a definite position. It has no length, breadth and thickness. A point is zero-dimensional, |
Line | A line is a straight. It has no thickness. It has neither a beginning nor an end. A line is one-dimensional. A and B are two points on the line. $$\text {The line is denoted by }\overleftrightarrow{AB}$$. |
Line segment | A part of a line is a line segment. $$\text {This line segment is denoted by }\overline{AB}$$. A line segment has a beginning and an end. |
Ray | This is a ray. It begins at point A and it has no end point. B is a point on the Ray. $$\text {The ray AB is denoted by }\overrightarrow{AB}$$. |
 | Whenever two line segments meet they meet at a point. The line segments AB and PQ meet at a point R. |
 | Two lines can also meet at a point. |