basic geometrical ideas

class 6 ncert basic geometry maths

1. BASIC GEOMETRICAL IDEAS

2. GENERAL DETAILS Pupil teacher’s name : Pooja bindal Shalu verma

3. GENERAL DETAILS Subject : Mathematics Class : 6 th Topic : B asic geometrical ideas Duration : 35 minutes

4. GENERAL OBJECTIVES Pupil will be able to :- Understand the properties of quadrilaterals. Distinguish between different types of quadrilaterals. Grasp the concept of symmetry in different types of quadrilaterals

5. What is geometry ? Geometry is the branch of mathematics which deals with properties and relations with the lines , angles ,surfaces and solids. Just as Maths deals with numbers , geometry deals with figures , points and lines…….

6. POINT A point is usually represented by a small dot. By a sharp tip of the pencil, mark a dot on the paper. Sharper the tip, thinner will be the dot .

7. Line Segment A line segment corresponds to the shortest distance between two points. The line segment joining points A and B is denoted by AB

8. This shortest join of point A to B (including A and B) shown here is a line Segment. AB

9. Line A line is obtained when a line segment like AB is extended on both sides indefinitely ; it is denoted by AB or sometimes by a single small letter like l . A B AB

10. Intersecting Lines Two distinct lines meeting at a point are called intersecting lines . L1 L2 P

11. Parallel Lines Two lines in a plane are said to be parallel if they do not meet . Identify parallel lines

12. Ray A ray is a portion of a line. It starts at one point (called starting point) and goes endlessly in a direction . A P Two points are shown on the ray. They are (a) A, the starting point (b) P, a point on the path of the ray. We denote it by AP.

13. some models for a ray Beam of light from a light house Ray of light from a torch Sun rays

14. POLYGON A polygon is a simple closed curve made up of line segments. (i) The line segments are the sides of the polygon. (ii) Any two sides with a common end point are adjacent sides . (iii) The meeting point of a pair of sides is called a vertex . (iv) The end points of the same side are adjacent vertices. (v) The join of any two non-adjacent vertices is a diagonal.

15. Angles An angle is made up of two rays starting from a common end point. Two rays OA and OB make ∠AOB(or also called ∠BOA ). o A B ∠AOB ANGLE AOB

16. The meeting point of a pair of sides is called a vertex. The end points of the same side are adjacent vertices

17. Triangles A triangle is a three-sided polygon The three sides of the triangle AB , BC and CA . The three angles are ∠ BAC, ∠BCA and ∠ABC . The points A , B and C are the vertices of the triangle

18. Quadrilaterals A four sided polygon is a quadrilateral It has 4 sides and 4 angles. F our sides AB, BC , CD and DA . Four angles ∠A , ∠B, ∠C and ∠D

19. AB and DC are opposite sides ∠A and ∠C, ∠D and ∠B are opposite angles

20. Circles A circle is a simple closed curve which is not a polygon. Parts of circle 1.Centre - The fixed point 2.Radius- fixed distance 3.Diameter -A diameter is a chord passing through the center 4.Chord-line segment joining any two points on the circle. 5.Circumference – distance around the circle.

21. The fixed point is the center The fixed distance is the radius A diameter is a chord passing through the center of the circle. A chord of a circle is a line segment joining any two points on the circle. The distance around the circle is the circumference. 1.Centre - o 2.Radius - r 3.Diameter - d 4.Chord - ca 5.cirumference o r d c a

22. A region in the interior of a circle enclosed by an arc on one side and a pair of radii on the other two sides is called a sector. A region in the interior of a circle enclosed by a chord and an arc is called a segment of the circle.

23. Learning outcome Students will be able to Understand the concept of point , line , line segment , ray ,angle , triangle , quadrilateral and circle. Apply the knowledge in different situations.

24. Thank you