Bellwork:

What is the formula for a) the circumference of a circle and b) the area of a circle?

What is the area of a circle with circumference 18 cm?

What is area of 1/3 of that circle?

11.6 Areas of Circles, Segments and Sectors

Students will be able to find the areas of circles, segments & sectors of circles.

Definition: Sector (Toolbox – back of paper!)

A sector of a circle is a region bounded by two radii of the circle and the arc intercepted by those radii.

Definition: Segment (Toolbox—back of paper!)

A segment of a circle is the region bounded by a chord and its minor (or major) arc.

Think about it!

Find the area of a circle with diameter 16 cm.

What would be the area of a sector of the circle above if the angle between the two radii of the sector was 90 degrees?

Draw the picture here:

Sector Area

Write a proportion or formula for finding the sector area.

Give this one a shot!

Tom has ordered a 20 inch pizza. If he ate 40 degrees of the whole pizza. How much in square inches of the pizza did he eat?

How would you find this area?

Find the area of the segment (that is the shaded region).

Hint: Thinking caps

required!

Segment Area

Describe in words how one would find the segment area:

This one will be no problemo!

Find the area of the shaded region.

Homework

Pg. 539 # 3 , 4, 9 -11, 12a, 14 a, d and f, 15, 18a

Extra Credit: A

complete written

solution to # 22

How about this one?

Find the area of the shaded region.