1. The extraordinary shape Circle

2. Why circle is extraordinary? Circle is much different shape from the others because:  It has no sides  Has infinity axis of symmetry.  Have other parameters then other figures.

3. Parameters of circle 1. The middle of circle – We mark it with letter „O” or „S” 2. Diameter – We mark it with letter „D”. It passes through the middle of the circle, it’s straight and her points are on the circle’s line. 3. Radius – It’s just the half of the diameter. We mark it with letter „R” and it goes from the middle of circle to the circle’s line.

4. Perimeter and Area of circle How to count the perimeter of circle? P = 2 πr O – perimeter Pi number = 3,14 r = radius of the circle How to count the area of circle? P = πr2

5. Checking task Count the area of circle when the radius is 6 cm. We must use the definition here. P = 3,14 x 62 P = 3,14 x 36 P = 113,04 cm2 The area of circle is 113,04 cm2

6. Task 2 Count the perimeter of circle when the radius is 9 cm. (In some cases you can use the symbol π instead of number 3,14) O = 2 πr O = 18 π The perimeter is 18 π cm.

7. Thank You for watching! Jakub Samul