Download - Circles g7

Transcript
Page 1: Circles g7

Circles

Page 2: Circles g7

What is the circle?

• The set of all points those are equidistant from a fixed point is called a circle.

• The fixed is called center of the circle.• The line segment between two points on the

circle which is passing through the center is called the diameter.

• The line segment between any point on the circle and the center is called the radius (plural radii).

Page 3: Circles g7

circle

The fixed point(center)

diameterradius

Page 4: Circles g7
Page 5: Circles g7

Circumference:

• The circumference is the length of the outer boundary of a circle.

Page 6: Circles g7

Finding the circumference

• The circumference of a circle is given by the formula C = πD, where C is the circumference and D is the diameter of a circle.

• Notice that D = 2xRadius = 2r• π : an irrational number which is

approximately equal to 3.14.

Page 7: Circles g7

Example:

• Find the circumference of each of the following circles.

Page 8: Circles g7

Find the circumference of each of these circles.

Page 9: Circles g7

Find the perimeter of each of the shapes below. (Remember to add the lengths of the straight sections.)

Page 10: Circles g7

A scooter tire has a diameter of 32 cm. What is the perimeter of the tire?

Find the circumference of the Ferris wheel shown below.

Page 11: Circles g7
Page 12: Circles g7

Area of a circleIf the circle is divided into smaller sectors, the curved sides of the sectors become straighter and, hence, the shape is closer to a perfect rectangle.

Page 13: Circles g7

Finding the area of a circle

• The area of a circle, A, can be found using the formula A = π r2 , where π is a constant with a value of approximately 3.14 and r is the radius of the circle.

Page 14: Circles g7

Example:

• Find the area of each of the following circles.

Page 15: Circles g7

Find the area of each of these circles.

Page 16: Circles g7

Find the area of each of the shapes below.

Page 17: Circles g7

Definition: An annulus (plural annuli) is the shape formed between two circles with a common center (called concentric circles).

Page 18: Circles g7

Find the area of the annulus for the following sets of concentric circles.

Page 19: Circles g7

Find the area of the following shapes:


Top Related