## Friday, February 11, 2011

### Alec's Surface Area Post

First find the radius
r=d/2
r=7/2
r=3.5

Since I have the diameter already I'm going to find the circumference
c=πd
c=3.14x7
c=21.98

Then find the area of the circle
a=πrr
a=3.14x3.5x3.5
a=38.47 square cm ( I round up to the nearest hundredths)

I now have the area of the 2 circle so I need to find next is the area of the square
a= lxw (l is the circumference)
a=21.98x7
a=153.86 square cm.

Add the area of the 2 circle and the rectangle
38.47+38.47+153.86= 230.8square cm
TSA= 230.8square cm

I'm gonna use another way to solve this question
(2πrr) + (2rπh)
(2x3.14x3x3) + (2x3x3.14x5)
=56.52 =94.2
Then add those 2 answer to get the TSA
56.52+94.2=150.72square cm.

(2πrr) + (2rπh)
(2x3.14x6.5x6.5)+(2x6.5x3.14x20)
=265.33 =816.4
265.33+816.4=1081.73square cm
TSA=1081.73square cm

r=d/2
r=20/2
r=10cm
(2πrr)+(2rπh)
(2x3.14x10x10)+(2x10x3.14x40)
628+2512
3140cm^2

r=d/2
r=30/2
r=15
(2πrr)+(2rπh)
(2x3.14x15x15)+(2x15x3.14.20)
1413+37680=39093
The fat one is the better deal because it has more capacity.

#### 1 comment:

1. Good job Alec, you shown your work very neatly and detailed. For improvement is to maybe use your options like italicizing, using colours or making some things bold and maybe having a darker picture. But this was a great post with amazing work shown very well, keep up the good work Alec!