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Thursday, September 29, 2011

Kim's Blog Post

Today we had a quiz on surface area.

Question 1

Draw the net of the exposed areas of this shape. Assume that this shape is resting on a table.

This is the net.

There are only three rectangles because the base is not exposed. Since it's resting on a table, you can't touch it.

Question 2

Calculate the surface area of the exposed areas.

S.A. = 3(lw) + 2(s²)
= 3(4)(2) + 2(2²)
= 3(8) + 2(4)
= 24 + 8
= 32m²

Question 3

If a can of paint covers 0.5m², how many cans would it take to cover 32m²?

1 can = 0.5m²
x cans = 32m²
32 = 0.5x

32/0.5 = 0.5x/0.5
64 = x

It will take 64 cans to cover this shape.

After the quiz we learned how to find the surface area of a shape after you put two shapes together.

We have these two shapes and we have to put them together.

When they're connected they look like this.

The red part is the part that is covered. (On Shape 1, the red part is the same as the back.)

Shape 1

Shape 2

So to find the surface area of the the connected shape, it's easier to do two separate formulas then subtract the area that's touching.

Shape 1
S.A. = 2(s²) + 4(lw)
= 2(2²) + 4(3)(2)
= 2(4) + 4(6)
= 8 + 24
= 32u²

Shape 2
S.A. = 2(lw) + 2(lw) + 2(lw)
= 2(1)(4) + 2(2)(4) + 2(1)(2)
= 2(4) + 2(8) + 2(2)
= 8 + 16 + 4
= 28u²

32 + 28 = 60u²

Area covered = 2(s²)
= 2(2²)
= 2(4)
= 8m²

60 - 8 = 52u²

The surface area of the shape is 52u².

Here's another way to find out the surface area.

S.A. = 2(s²) + 4(lw) + 2(lw) + P(h) - 2(s²)
= 2(2²) + 4(2)(3) + 2(1)(2) + 6(4) - 2(2²)
= 2(4) + 24 + 4 + 24 - 2(4)
= 8 + 24 + 4 + 24 - 8
= 52u²


- Go on
- Sign in and go to "Set tasks" in Mathematics.
- Do all the homework that Mr. Backe assigned before if you haven't finished it.
- Be ready for the test next week.
- Come to Mr. Backe if you need any help with anything.

The person that I choose to do the next blog post is Chelsea.


  1. Good post Kim. I like how you added pictures and that everything was organized.I also like how you made the answers bold so that it would stand out. Good job.

  2. Good job Kim. Your post was organized and well done, I like your pictures, they are clear and easy to understand. I like how you used italics instead of colour to make key words stand out, but maybe next time you could add colour to those also so they are more recognizable as key words. Also like Tianna said, I like the bold answers, it helps them to stand out. Overall great job. :)

  3. Great post, Kim! Everything was organized and neatly made. The pictures were clear, and easy to understand. You did italize and bolded the key words, but I also would have liked to see some colour in them, as I had a bit of a hard time recognizing the words. Nonetheless, good job!

  4. Great job, Kim. Everything was well organized and the pictures were carefully drawn and easily understandable. It would have been nice if you added colour to your post, and possibly the measurements for the figures.

  5. Good job Kim. The pictures were neat and clear but they did not have measurements. Maybe next time you could put that in. I like how you put two seperate methods for the last question. That was pretty good. Maybe (as the other commentors have said) you could use some colour to highlight certain words and points. Other than that a great post.

  6. Good job Kim!! Great job on explaining all the notes. Also good job on the pictures they are great but next time add the measurements so it will be easier to understand but great job anyway

  7. I really liked your post Kim ! Everything was well done but you could of put the measurements of the shape where we needed to put them together, other then that well done !

  8. Great Job Kim! Your work was neat, included all the information and work we did in class. Your formulas for the shapes made sense and I knew what part of the shapes the formulas were for because it was very neat. Question 3 was a bit confusing because of the formulas, and maybe next time you could add a bit of colors for the words but otherwise your pictures were fantastic, and thank you for adding what we needed to do for homework. Great Job!

  9. Good job Kim! The post is done well done. I like the pictures you made, how you added what was for homework, and how you put to ask for help if we don't understand something. I also like how you made some words/numbers bold. Next time add colour. Overall good job!

  10. Good Job Kim! The post look very neat. The pictures you made made your blog to be easily understand and presentable. Keep it up

  11. Good job Kim! I like how your pictures were organized! They were very neat, next time you can add some colors on the words! Good post though! :)

  12. Nice Job Kim! Good job on making your pictures! Next time you should add colour. Your information is very clear and understandable! Keep it up!

  13. Just AWESOME. Very well organized and just legitimately marvelous pictures. You've explained everything very well. I applaud the fact you added our homework. OUTSTANDING BRUH!

  14. Good job Kim. I like the pictures it's very nice and it's very easy to understand.

  15. Great job Kim ! Your pictures are awesome. They are very clear and understandable. If you can, try putting in the measurements of each side. Also, put colors to the words that are important so they are easy to remember. Good job in this post !