Perimeter, Area, Volume and Relationships of Circular figures

1
Lesson 2

• Perimeter, Area, Volume and Relationships of
  Circular figures

2
Perimeter and Area
Perimeter (circumference)
Area
3

• All Answers that contain pi must be given in two
  answers.
• Exact Value which contains pi.
• Approximate which is using the pi button on your
  calculator and rounding to the thousandths (three
  decimal places).

4
Circle Relationships

• Given a circles area/circumference, we can find
  the other by setting up an equation to find the
  radius first.
• The area of a circle is 289p in2. Find its
  circumference.
• A 289p
• pr2 289p
• r2 289
• r 17 in

C2rp 2(17)p 34p in
5
Practice

• The area of a circle is 49p cm2. Find its
  circumference.
• The circumference of a circle is 12p cm. Find its
  area.

6
Volume

• H altitude, perpendicular to the base

Volume is 3D, so our units are cubed
7
Practice

• The volume a circular cylinder is 968pft3. What
  is the height of the cylinder
• V 968p
• pr2H 968p
• r2H 968

(11)2H 968 121H 968 H 8 ft
8
Circular Sectors
arc measure central angle
A sector is a fraction of a circle, so the area
of a sector is a fraction of the circles area.
Area of sector
9
More Circular Sectors
It works the same for arc length. Since an arc
is a fraction of a circle, the arc length of a
sector is a fraction of the circles
circimference.
Arc Length
10
The radius of a circle is 10cm. Find the length
of a 45º arc and the area of a 45º sector.
Arc length
Area
11
Problem Set 2Skip 9-22