1 / 16

Circles

Circles. A circle is a shape with all points the same distance from its center. The distance around a circle is called its c ircumference . The distance across a circle through its center is called its diameter.

debra-spence
Download Presentation

Circles

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Circles

  2. A circle is a shape with all points the same distance from its center. The distance around a circle is called its circumference. The distance across a circle through its center is called its diameter.

  3. (pi) is the ratio of thecircumference of a circle to its diameter. For any circle,if you divide its circumference by its diameter, you get avalue close to 3.14159. This relationship is expressed in thefollowing formula: C/D = where C is the circumference and D is the diameter.

  4. The radius of a circle is the distance from the center of a circle to a point on the circle. If you place two radii end-to-end in a circle, you would have the same length as one diameter. So a circle's diameter is twice as long as its radius.

  5. The formula for the circumference of a circle is given by either :

  6. Example : The diameter of a circle is 3 cm. What is itscircumference? (Use = 3.14) Solution: C = d C = 3.14 · (3 cm) C = 9.42 cm 3 cm

  7. Example : The radius of a circle is 2 in. What is itscircumference? (Use = 3.14)

  8. Example : The circumference of a circle is 15.7 cm. What isits diameter? (Use = 3.14) • C = d 15.7 cm = 3.14 · d d = 15.7 cm ÷ 3.14 d = 5 cm

  9. The area of a circle is the number of square units inside that circle. If each square in the circle below has an area of 1 sq.cm, you could count the total number of squares to get the area of this circle. If there were a total of 28.26 squares, the area of this circle would be 28.26 csq.m

  10. The area of a circle is given by the formula

  11. Example : The radius of a circle is 3 in. What is its area?(Use = 3.14) • Solution: A = · r · r • A = 3.14 · (3 in) · (3 in) • A = 3.14 · (9 sq.in) • A = 28.26 sq.in

  12. Example: The diameter of a circle is 8 cm. What is its area?(Use = 3.14) • r = 4 cm • A = · r · r • A = 3.14 · (4 cm) · (4 cm) • A = 50.24 sq.cm

  13. Example: The area of a circle is 78.5 sq.m. What is its radius? (Use = 3.14) • Solution: A = • 78.5 sq.m = 3.14 · • 78.5 sq.m ÷ 3.14 = • 25 sq.m = • r = 5 m

  14. Find the area of the rectangular piece of metal after the 2 circles are removed. 16 cm 10.00 cm 28.00 cm 45.00 cm

  15. Find the perimeter and area of the shape.

  16. A belt connecting two 9-in-diameter drums on a conveyor system needs replacing. How many in long must the belt be if the centers of the drums are 10 ft apart? Round to tenths. 9 in 9 in 10 ft

More Related