2. Confidential2 Warm Up 1.Find the Circumference of a Circle with a radius of 12.5 miles 2. Find the Circumference of a Circle with a radius of 21 meters. 3. Find the Circumference of a Circle with a radius of 8 ¾ feet. 4.If the radius of the Circle in the last question is doubled, is the circumference doubled? Why or Why not? 5.Find the circumference of a Circle whose Diameter is 10.3cm.

3. Confidential3 A circle is a set of points in a plane at a fixed distance from a fixed point. The fixed point is called the center of the circle The perimeter of the circle is called the circumference of the circle Let’s summarize what we have learnt today

4. Confidential4 Diameter (AOC) Chord which passes through the centre of the circle (twice the radius) Chord (DF) Straight line joining any two points on the circumference Sector (shaded area) Part of the circle bounded by two radii and an arc cut off by it Arc (DEF) Part of the circumference C A D F Segment (shaded area) Part of the circle bounded by a chord on one side and an arc on the other side. Radius (OH) Distance between the centre and any point on the circumference (half the diameter) E G H O B Quadrant (shaded area) Sector in which the two radii are perpendicular to each other Parts of a Circle

5. Confidential5 1.The ratio of circumference to diameter is a constant for a given circle which is denoted by the Greek alphabet  (Pi) 2.The perimeter of a circle is called its circumference. Circumference of a circle, C = 2  r or C =  d 3.Area of a circle, A =  (radius)² or A =  r² 4.Radius of the circle, r =  A/  5.A sector of a circle is a region enclosed by an arc of a circle and the two radii to its end points. 6.Area of a sector, A = 1/2 * radius * length of the arc

6. Confidential6 What are 3D figures?- 3D figures are figures which have length, width and height. In the term 3D, 3 refers to the numbers of dimensions and D refers to dimension. Examples of 3D figures : Cone, Cube, Cylinder, Pyramid, Rectangular Prism and Sphere.

7. Confidential7 Related vocabulary Face: A face is a flat surface of a 3D figure. Edge: An edge is the line segment formed where two faces meet. Vertex: A vertex is a point where two or three edges meet. Two or more are called vertices. edge face vertex

8. Confidential8 Cone A cone has only one face which is a circle. A cone has one vertex. A cone has no edges.

9. Confidential9 Cube A cube has six faces. All the faces are squares. A cube has 8 vertices. A cube has 12 edges.

10. Confidential10 Cylinder A cylinder has 2 faces. Both the faces are circles. A cylinder has no vertex. A cylinder has no edges.

11. Confidential11 Square Pyramid A square pyramid has 5 faces of which 4 are triangles and one is square. A square pyramid has 5 vertices. A square pyramid has 8 edges.

12. Confidential12 Rectangular Prism A rectangular Prism has 6 faces. All the faces are rectangles. A rectangular Prism has 8 vertices. A rectangular Prism has 12 edges.

13. Confidential13 Sphere A sphere has no face. A sphere has no vertex. A sphere has no edges.

14. Confidential14 Practice Name the 3D figure that each object looks like. Sphere Cube Cylinder

15. Confidential15 Practice Name the 3D figure that each object looks like. Rectangular PrismSquare Pyramid Cone

16. Confidential16 Your Turn 1)Name the 3D figure. 2)How many faces does it have? 3)How many edges does it have? 4)How many vertices does it have?

17. Confidential17 Your Turn Match the figures. 5)Cube 6)Cylinder 7)Square pyramid 8)Cone 9)Sphere 10)Rectangular Prism

18. Confidential18

20. Confidential20 Q1. James painted a box shaped like a cube. Each face was a different color. How many colors did he use?

21. Confidential21 A child’s toy game contains a wood frame with cut-out shapes and some blocks. Name the shape of a block that will fit exactly through both the square and a Circle. Q2.

22. Confidential22 Q3. Name the 3D figures used to make the object.

23. Confidential23 Let Us Review  3D figures are figures which have length, width and height.  A cone has only one face, one vertex and has no edges.  A cube has six faces, 8 vertices and 12 edges.  A cylinder has 2 faces, 0 vertices and 0 edges.

24. Confidential24 Let Us Review  A square pyramid has 5 faces, 5 vertices and 8 edges.  A rectangular Prism has 6 faces, 8 vertices and 12 edges.  A sphere has no face, no vertex and no edges.

25. Confidential25