## Tuesday, October 5, 2010

### Brendan's Blog Post

In this Blog Post, I will be going over Question 3 on page 8 in your homework book.
The Question is "Which container has the greater surface area?" and "How much more surface area does one have than the other?". It also told me to round to the nearest tenth.
The first container looks like this.

I found the surface area of this cylinder by making it's net, and then finding the surface area of the circle and rectangle.
The net of this cylinder looks like this ..

S.A of the circle = Pi x r squared
= Pi x 5 squared
= Pi x 25
= 78.5 squared cm
Before I could find the surface area of the rectangle in the net, I needed the formula for the diameter of the the circle which was ..
d of the circle = r x 2
= 5 x 2
= 10 cm
and the circumfrence of the circle for the other side of the rectangle.
C of the circle = Pi x d
= Pi x 10
=31.4 cm
Now that I found out the circumfrence of the circle, I can figure out the surface area of the rectangle in the net.
S.A of the rectangle = l x w
= 14 x 31.4
= 44 squared cm
So the TSA (total surface area) of the cylinder is ..
TSA = [2(S.A of cirlce)] + (Area of rectangle)
= [2(78.5)] + (44)
= 157 + 44
= 201 squared cm
The second container looked like this.

I found this shape's surface area by making it's net, and then adding the surface area for all three different sides, and the multiplied the answer by two.

This is what the net looks like ..

T.S.A of rectangular prism = 2(14 x 5) + (5 x 8) + (14 x 8)
= 2(70) + (40) + (112)
= 2 (222)
= 444 squared cm
I know the second container's surface area is more than the first container's surface area by 241 squared cm because 444 - 201 = 243 squared cm.
Thank you for reading my blog post.
Do not be afraid to help me learn by correcting me!