## Sunday, February 28, 2010

### Sharmaine's Surface Area Growing Post

Formula on find surface area of a Rectangular Prism:

A= L x W

Top

A= L x W

A= 8cm x 16cm

A= 128cm2 A=

Front

A= L x W

A= 2cm x 16cm

A= 32cm2

Side

A= L x W

A= 2cm x 8cm

A= 16cm2

TSA(total surface area)= 128 + 128 + 32 + 32 + 16 + 16

TSA= 352cm2

Triangular Prism:

Formulas on finding the surface area of a Triangular Prism:

-A= L x W

-A= B x H / 2

A= L x W

A= 2.5cm x 10.6cm

A= 26.5cm2

A= L x W

A= 2.5cm x 8cm

A= 20cm2

A= L x W

A= 2.5cm x 7cm

A= 17.5cm2

A= B x H / 2

A= 7cm x 8cm / 2

A= 56cm / 2

A=28cm2

TSA= 26.5 + 20 + 17.5 + 28 + 28

TSA= 120cm2

Cylinder:

Formulas on finding the surface area of a cylinder:

-(pi)d= C

-r=d/2

-r2=d

-A= (pi) x r x r

-A= L x W

(pi)d= C

3.14 x 5cm

15.7cm

r=d/2

r=5/2

r= 2.5cm

Area of a circle

A=(pi) x r x r

A= 3.14 x 2.5cm x 2.5m

A=19.625cm2

Area of a Square

A= L x W

A= 7cm x 15.7cm

A= 109.9cm2

TSA = Area of a square + Area of a circle + Area of a Circle

TSA= 109.9 + 19.625 + 19.625

TSA= 149.15cm2

COMMENT! :D

### Mary Jane's Surface Area Growing Post

**Triangular Prism:**

**Formulas:**

**TSA**= A1 + A2 + A3 + A4 + A5

**triangular prism**you have to find the area of each of the

**five faces**. After finding all the areas, you then have to

**add**all of them up to get the TSA.

## Saturday, February 27, 2010

## Thursday, February 25, 2010

### Ralph's Surface Area Growing Post

To find the area of a square you use this formula

a= lxw

Using this formula I can find the area of a rectangular prism. First I have to make a net of the rectangular prism then I use the formular for each face on the prism. After I find the area of all the faces I add them all up to get the Total Surface Area.

TSA=50+50+30+30+15+15

TSA=190cm(2)

Triangular Prism:

To find the area of a triangle you use this formula

a=lxw/2

Using this formula I can find the area of a triangular prism. First I have to make a net of the triangular prism then I use the formular for each face on the prism. I used the rectangular prism formula when there was a square and used the triangular prism formula when there was a triangle. After I find the area of all the faces I add them all up to get the Total Surface Area.

TSA= 1.89+0.98+1.61+1.61+1.61

TSA=7.7cm(2)

Cylinder :

For the cylinder you use 2 formulas.

To find the circumference you use this formula. C = pi x r x r

If you need to find the area of the circle you use: a = (pi) x d

Using this formula I can find the area of a triangular prism. First I have to make a net of the cylinder. Next I used another formula to get the diameter of the cyclinder (which would be r x 2 = d). After that I used the radius to calculate the circumference. Next I used the diamter to find the area of the circle. Next I used the rectangular prism formula to figure out the rectangular part of the net. Finally I added the 2 circles and the rectangular part of the net and got the TSA.

TSA=314+314+1381.6

TSA=2009.6

How to find the TSA of a cylinder

How to find the TSA of a trianglar prism:

How to find the TSA of a rectangular prism:

Thanks for reading! Leave a comment below!

## Sunday, February 21, 2010

### Elaine's Scribepost for February 18, 2010

3. Sketch a net for each object.

a) hockey puck

b) chocolate bar

c) jewellery box

5. Draw a net on grid paper for a rectangular prism with the following measurements:

- length is 6 units

- width is 4 units

- height is 2 units

8. A box of pens measures 15.5 cm by 7 cm by 2.5 cm. Draw a net for the box on a piece of centimetre grid paper. Then, cut it out and fold it to form the box.

as a net:

as a rectangular prism:

THANKS FOR READING MY SCRIBEPOST!!

## Saturday, February 20, 2010

### Ralph's Surface Area Scribepost Feb 18

a)hockey puck

measurements on the net.

a) Tennis ball case

Sketch all of them. The first one is done

for you.

## Friday, February 19, 2010

### Scribepost for February 18, 2010

Hi everybody today at class we had to do some questions in our math text book.

So for the people who are doing the blog they have to do 3 questions.

So I'm doing questions 3,4&6

So number 3

Sketch a net for each object.

Number 4

Draw the net for each object. Label the

measurements on the net.

Number 6

6. a) Draw the net on grid paper, as shown.

Cut along the outside edges of the net

and fold to form a 3-D object.

This is how would it look like.

b) What is this object called?

Triangular Prism

So I'm done.

Tell me what I screwed up and what I did good.

## Wednesday, February 17, 2010

### Sharmaine's scibe post for feb.17,2010

5. Draw each 3-D object using the views below.

11. An injured bumblebee sits at a vertex of a cube with edge length 1 m. The bee moves along the edges of the cube and comes back to the original vertex without visiting any other vertex twice.

a) Draw diagrams to show the bumblebee’s trip around the cube.

b) What is the length, in metres, of the longest trip?

The longest trip was 8m.