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Saturday, September 24, 2011

Olivia's Blog Post

Today we went over our homework from yesterday.

Mr. Backe had given us an isosceles triangular based prism to find the surface area for. We were supposed to use the Pythagorean Theorem to find the length of the hypotenuse.

Here is a net of the triangular prism:

Here is the 3D drawing of the triangular prism:

To find the surface area of this triangular prism, you must first find the length of the hypotenuse for the triangle

Pythagorean theorem: 
 a² + b² = c² 
3² + 4² = c² 
9 + 16 = c² 
√25u² = √c² 
5u = c

Sorry if the letters are small and fuzzy. :S

Now you can find the surface area for the triangular prism
Use the formula, 
 S.A. = A1 + A2 + A3 + 2(A4)

Now plug in the numbers and solve the surface area: 
* pythw = Pythagoras(width) 

 S.A. = A1 + A2 + A3 + 2(A4) 
         = s² + lw + pythw + 2(bh/2) 
         = 3² + (3)(4) + (5)(3) + 2[(4)(3)/2] 
         = 9 + 12 + 15 + 12 
         = 48u²

Next, we went over question 4. a) from page 32. 
Here is a net of the shape:

To find the area for this shape, Mr. Backe made us find the faces that were similar to the Back and Base, and put them together as 2(A1), 2(A2), etc.

Sorry, this one is really complicated, I didn't have enough room, though I thought I did.

The formula you use to find the surface area of this shape is:

S.A. = 2(A1) + 2(A2) + 2(A3) + 2(A4)
            = 2(lw) + 2(lw) + 2(lw) + 2(s²)
        = 2(4)(5) + 2(2)(5) + 2(1)(2) + 2(2²)
        = 2(20) + 2(10) + 2(2) + 2(4)
        = 40 + 20 + 4 + 8
        = 72u²

If you got 76u², that was wrong, because the two shapes have a different net:

As you can see, the nets are different, causing the surface area to be different.

Next, we talked about this shape from question 5. a) on page 32 (it was turned vertical):

Mr. Backe asked us if the view of that shape was the same as the view as this shape (turned vertical):

At first, the majority of the class thought that the view was different, but then we realized that the view was the same

Mr. Backe then asked us to draw a net for the views of both of the shapes:


Both shapes have the same view, so therefore, the surface area is still the same

To solve: 
S.A. = 2(A1) + 2(A2) + 2(A3) 
        = 2(s²) + 2(lw) + 2(lw)
        = 2(2²) + 2(2)(3) + 2(3)(2)
        = 2(4) + 2(6) + 2(6)
        = 8 + 12 + 12
        = 32u²

 - journal (also previous day's journal if you didn't do it) 
- Textbook page 32 - 33 # 4-9 
- homework book chapter 1.3 for extra practice if you haven't already finished it 

*Hint: use graph paper to draw out the nets of the shapes to help you

Have a great long weekend everybody! :)


  1. Great post Olivia! I like how used colours on certain words to make them stand out. I also like how added pictures to make it easier to understand. Thank you for posting the homework. Everything was well done.

  2. Wow! That was a great post! It had everything that we did in class and it was explained and shown perfectly. You also used colour on certain words which was good. Great job putting up the homework. I almost forgot about it. Well done and keep it up!

  3. Nice post, Olivia! I like how you used different colours on important words to make them stand out. The pictures are clear and easy to understand. Thanks for putting up the homework as well! Great job.

  4. Good job,Olivia!! I really like your post it was very detailed. I like how you showed your work and explained what you were talking about. Also good job on posting what the homework is.

  5. Great post Olivia! You explained everything with exact information, you included pictures that I found were very easy to understand, and you also used the right amount of colors. Your blog had no mistake, but a few of your pictures were a bit small and fuzzy but it may be just how the computer shows it, thank you for including the homework for the weekend in your blog I forgot to write it down in my agenda. Your post was GREAT! Good Job Olivia!

  6. I like how you explained everything that we looked over during the class. Also the pictures really helped me understand how to make a the net and how to find the surface area of a shape that's missing a piece. Overall it was a really good post.

  7. Great post, Olivia. You explained everything wonderfully and in a way anyone could understand. The pictures were very informative and overall the post was very organized. I would suggest that you explain the reason we find the hypotenuse is because it would equal a side length for one of the faces. I would also suggest that using colour for each area of the net with an optional legend on the side instead of labeling would keep everything from cramping up. I would also think it would be better if you'd choose one of either highlighting the words or actually having the words a certain color. I found the sudden changes a bit disorientating.

  8. Good Job Olivia!! I like how you used different colours to make other words stick out. It made everything easier to understand. You also made beautiful pictures to show your work. That also made things easier. Your post was easy to understand and very organized. I cant tell you put a lot of effort into it. Good Job!

  9. Great job Olivia! I like how you changed the colour of the font of the important words. I also like pictures you made. The 7th picture is kind of confusing, its a bit cluttered. Overall great job!

  10. Good Job Olivia! I like how you put everything we learned from the class. Also the pictures are great, it help me to understand it more. Keep it up

  11. Good Job Olivia, I like how you changed the font and the font color to make things stand out more. You can try to make your pictures not so squished up, just like how Colleen said. Good job on the post though! :)

  12. Nice Job Olivia! Good Job on the pictures but next time don't make them squishy. I like how you made the font's different sizes! Also you post is neat and understandable.

  13. Awesome job on this post Olivia! Neat idea on changing important words, to make them more noticeable and special. Well done.

  14. Good job Olivia ! I like your pictures. They are very neat and understandable. I also liked how you highlighted important words and phrases. Good job !