## Friday, February 26, 2010

### Carla's Surface Area Growing Post

Rectangular Prism

Net

Formulas
To get the area of a rectangle, use:
a = l x w
To get the total suface area, use:
TSA = square + square + square

Solution (click to make it bigger.)

Triangular Prism

Net

Formulas
To get the area of a triangle, use:

a = b x h
To get the area of the rectangle, use:
a = l x w
To get the total surface area, use:

Solution
( click to make it bigger.)

Cylinder

Net

Formulas
To find the area of a circle, use:
a = π•r•r
To find the circumference of a circle, use:
C =π•d
To find the area of a rectangle, use:
a = l x w
To find the total surface area, use:

Solution

### Surface Area Growing Post

3-D Rectangles

This is a rectangular prism:

This is a rectangular prism net:

Here are the measurements needed to get the total surface area (TSA) of the rectangular prism:

Here are the measurements on the rectangular net:

You use the formula L x W = a (Length times Width equals area of rectangle).

A = L x W
A = 2 x 3
A = 6cm

Since all the squares have the same measurements, we can add up the TSA now.

TSA = S1 + S2 + S3 + S4 + S5 + S6
TSA = 6 + 6 + 6 + 6 +6 +6
TSA = 36cm²

3-D Triangles

This is a Triangular Prism:

A Triangular Prism Net:

Triangle Prism with the measurements needed to get total surface area:

Net with measurements:

To get the total surface area, you need the formulas:
A = B x H / 2 (Area equals Base times Height divided by two)
A = L x W

To get the TSA, I'll first add 5cm, 6cm, 7cm because they're technically one line and that I can just multiply that number by the 3 cm instead of having to do it multiple times.

5 + 6 + 7=18cm

a = L x W
a = 3 x 18
a = 54cm²

a = B x H / 2
a = 6 x 5
a = 30 / 2
a = 15cm²

Since the other triangle has the same dimensions, we'll just add up the TSA.

TSA = S1 + S2 + S3
TSA = 15 + 15 + 54
TSA = 84 cm²

So the Total Surface Area of this triangle is 84cm².

Cylinders

This is a Cylinder:

This is a Cylinder Net:

This is the Cylinder with the measurements:

This is the Cylinder net with measurements:

These are the formulas needed to get the total surface area of a cylinder:
C = pi.d (Circumference equals pi times diameter)
R = D / 2 (radius equals diameter divided by two)
A = pi.r.r (area of circle equals pi times radius times radius)
A = LxW (area equals length times width)

How to get the total surface area:

We don't have all the needed measurements like circumference and radius yet, so we'll get them.

C = pi x d C = 3.14 x 10 C = 31.4cm

Remember, the circumference of a circle becomes the length of a rectangle.

r = D / 2 r = 10 / 2 r = 5cm

Now we can get the areas of the circle and rectangle.

A = pi.r.r A = 3.14 x 5 x 5 A = 78.5cm²

A = L x W A = 31.4 x 10 A = 314cm²

Now to add them all up:

TSA = C1 + C2 + S1 TSA = 78.5 + 78.5 + 314 TSA = 471cm²

And here's a video that me and Jim and Feppe made that shows what I did in this scribepost in video form. :D

### Elijah's Surface Area Growing Post

Rectangular Prism :

Rectangular Prism net:
Formula :

L x W = a
# x # = a
#cm = a

L x W = a
# x # = a
#cm(2) = a

TSA
= S1 + S2 + S3
= # + # + #
=tsa .

Solution :

Triangle Prism :

Triangle Prism net :
Formula :

area of rectangle :
= L x W
= # x #
= # cm

area of triangles :
= b x h / 2
= # / 2
= # cm(2)

TSA
=S1 + S2 + S3
=# + # + #
=#cm

Solution:

Cylinder:

Cylinder net:
Formula:

First find the cicumference of the circle to get the length of the rectangle.

πd = c
3.14 x # = c
# = c

Then find the area of the circle.

If you're given the diameter. You have to find the radius first.

d/2 = r
#/2= r
# = r

area of circle:
π x r x r = area of circle
3.14 x # = area of circle

# cm (2) = area of circle

Then find the Lateral Area of the square.

L x W= L.A
# of circle circumference x #= L.A
# cm= L.A

TSA
= circle + circle + L.A
= # + # + #
= # cm(2)

Solution:

Video :

Question 4

Question 7

## Friday, February 19, 2010

### Carla's Scribepost for February 19, 2010

5. Draw a net on grid paper for a rectangular prism with the following measurements: length is six units, width is four units, and height is two units.

a) It would look like this:

b) This object is a triangular prism.

a) Here's what it looks like. (click to make it bigger.)

b) They both make a triangular prism.

Thanks for reading my post. If you have anything to say, COMMENT!

## Wednesday, February 17, 2010

### Harvey's Scribepost for February 17 2009

These are the questions that I'm going to cover in this scribepost:

Here is a picture that I made that has the answers (sorry its hand drawn, its too hard to draw it on paint):

### Aldrine's ScribePost for Feb 17 2010

FOLDABLES!!!!!!!

Hi guys today we had to do our foldables on section 5.1

All of this on the key idea section including the question 1 &2

Question 1: My answer was, She is write because all you need to draw is top, front and side. You dont need to find the other side of top, front and side because you know that their the same size.

Question 2: My answer on question 2 was for me its right because by looking at it you have a good view and there wont be a problem by drawing it like that. if you want to see the other side of the book just imagine that your looking at it right now because there the same size if you turn it the other way.

### Jose's scribepost for February 17, 2010

Yesterday in math, our class moved onto a new unit called SURFACE AREA. We started off by creating our new foldable which turned out to be a RECTANGULAR PRISM.

All rectangular prisms have :
- 6 faces

- 8 edges
- 8 VERTICES

TO DESCRIBE A 3D OBJECT, COUNT ITS FACES, EDGES, AND VERTICES

DEFINITIONS :

face- A face is a flat surface of a 3D figure. EXAMPLE:
vertex - A vertex is a point where two or more straight lines meet. EXAMPLE:

edge: Is the line where two surfaces meet. EXAMPLE :
Net : It is a 3 dimension shape, that is flattened. FOR EXAMPLE WHEN YOUR MAKING A CUBE, ONCE YOU FIRST GET THE LAYOUT.

RECTANGULAR PRISM : A rectangular prism is a solid 3D object that has 6 faces that are rectangles. IT CAN LOOK LIKE MANY DIFFERENT WAYS.

After we found out those definitions, we had to draw 3 different other kinds of rectangular prisms and make a chart to write down the similarities and differences of them:
Similarities : Each of those RPS have 6 faces, 6 sides, 8 edges, and 8 vertices. Differences : Each look different from each other but are the same. The dimensions are different, and the face sizes are different

Once we finished that, we had to finish page 48 in our homework book. The very last thing we had to do was go home and find 3 rectangular prisms from our house and draw the SIDE, FRONT, and TOP view of them. These are the objects I chose :