## Monday, February 7, 2011

### Emily's Circle Surface Area Scribe Post

Notes:

-bases are circles
-diameter cuts a circle in half
is half the diameter
-circumference is the perimeter of a circle
-pi is the ratio between circumference/diameter or 3.14
-circumference, pi.d=c
-diameter, r.2=d or c/pi=d
-area of a square, pi.r squared or pi.r.r
-make a square with the radius and multiply by pi

EX.

Here are some questions we did in class:

Here is a LINK I found on area.

Here is a video:

What is the radius of a circle with a diameter of 8cm?

Create your own poll at Flisti.com

Cylinder Volume and Volume Problems

Volume Problem

d/2=r
8/2=r
4m=r

pi.r.r.h
(3.14x4x4)x10
(50.24m^2)10m
502.4m^3

Since it is a semi circular trough the area has to be divided by two.
502.4cm^3/2=251.2m^3

The volume of the semi circle is 251.2m^3

Volume Problem

To convert a meter to a centimeter you multiply it by 100.

0.25mx100=25cm

d=25cm

d/2=r

25/2=r

12.5cm=r

1mx100=100cm

height of cylinder= 100cm

0.35mx100=35cm

height of triangle=35cm

0.4mx100=40cm

base of triangle=40cm

1.4mx100=140cm

height of the triangular prism=140cm

pi.r.r.h

(3.14x12.5cmx12.5cm)x100cm

(490.625cm^2)x100cm

v=49062.5cm^3

bxh/2.h

(40cmx35cm/2)x140cm

(700cm^2)x140cm

v=98000cm^3

98000cm^3-49062.5cm^3=48937.5cm^3

48937.5cm^3 is needed to make the clay planter.

Here is the volume video I created: