10.7 Area of Circles and Sectors Brett Solberg AHS ‘11-’12

Warm-up

Today’s Agenda  pi  Area  circle  activity to discover  sector  segment  Quiz retakes  Test on Tuesday  CRT – 9 classes

Pi  ratio of circumference and diameter of a circle  d*π = c  π ≈

Area of A Circle  What is the radius of:  rectangle  parallelogram  triangle  trapezoid  What do these all have in common?  What is the formula for circumference?  Haw is the radius and diameter related?

Area of a Circle A = b*h

Area of a Circle  A = π r 2

Area Examples  Find the area if:  r = 3  r = 10  d = 14

Pizza Sizes

10”12”14”16”23” Area in π Area in decimal

Sector  A sector of a circle is a region enclosed by a central angle and an arc.

Area of a Sector

Example 3  Find the area of a sector with a radius of 6 and a central angle of 100˚.

Example 4  Find the area of sector ZOM in terms of π.

Segment  Region bounded by an arc and a line connecting the endpoints of the arc.

Area of a Segment area of a sector area of an isosceles triangle area of a segment

Example 5  Find the area of the shaded segment in terms of π, and then round to the nearest tenth.

Example 6  Find the area of the segments and the square. 10 in

Assignment  10-7 WS  EC Review pg 592 #1 – 20 all  EC Activity pg 575  Due Next Class  Worksheets  Chapter 1-10 Cumulative Review  Warm-ups