Scribe Post for October 27, 2009

Hey 9-05! Abby here with today's scribe post! First of all, I'd like to congratulate us 9-05 people. I think we did a really good job on the blog posts we've been doing.. So let's keep it up!

Okay, so today in math class, we went to the computer lab. First, we went over our homework from yesterday. I think some of us had a hard time with finding a fraction for a repeated decimal number with 3 numbers after the decimal. So here is the rule:













For this rule, you always want to multiply out all the repeating. So 0.2 repeated has to be multiplied by 10 to move the decimal down 1 place value. 0.43 repeated has to be multiplied by 100 to move the decimal down 2 place values, and 0.172 repeated has to be multiplied by 1000 to move the decimal down 3 place values.

x = o.2 (repeated)
10x = 2.2
9x/9 = 2/9
x = 2/9

x = 0.43 (repeated)
100x = 43.43
99x/99 = 43/99
x = 43/99

x = 0.172 (repeated)
1000x = 172.172
999x/999 = 172/999
x = 172/999


After that stuff, the people who needed help with the chessboard question went to the hallway with Mr. Backe so he could explain it to us. Here, I will explain and show you how to start the chessboard question.

1. A chessboard is a large square and is made up of 64 small squares. Consider only the first three rows of the chessboard.

a) Find the diagonals of all squares and rectangles possible in the first three rows. Arrange the squares and rectangles, from least to greatest, by length of their diagonals.

So first, we look at the first square on the chessboard:

Figure 1.0
















So, to find the diagonal for square number one, we have to use the a²+b² = c² formula. For the square, the dimensions are 1 by 1.

This is how you find the diagonal for square number one:
a²+b² = c²
1²+1² = c²
1+1 = c²



1.414 = c


Now, I'll show how to do the second part:

Figure 1.1















For the second square, we use the exact same formula, but the number change. B changes into 2 because the sides, which are all equal, are 1. And so, 1 side + 1 side = 2 sides. Or, to make easier 1+1=2!:
a²+b² = c²
1²+2² = c²
1+4 = c²



2.236 = c

Then, we have to do the rest of row number 1, which is the same procedure. When you go up one square, the b changes because the number of bottom sides are adding up. The a stays the same, and the hypotenuse grows larger. (I'm not sure if I made sense there..)

Figure 1.2







(sorry if the image is blurry!)


The second row has the same procedure except for the first diagonal because we already figured it out in row 1! (refer to Figure 1.1)

Figure 1.3











The third row ALSO has the same procedure except for the first diagonal because, like the second row, we already figured the first diagonal for the third row in row 1 (refer to Figure 1.1)

Figure 1.4









For the rest of the class, we went on mathlinks9.ca and shodor.org. In Mathlinks9.ca, we checked out some websites under student center; chapter 2; weblinks. Also, Mr. Backe told us to read a bit about Neil Barlett. On shodor.org, we did some games on fractions.

HOMEWORK:
-play some fraction games on shodor.org
-fill in math journal

Thanks for reading! If there's anything on here that doesn't make sense, or seems wrong, please comment and I'll try my best to correct my mistakes! Okay everyone, have a good evening!

The next scribe I choose for tomorrow is.. Nicky!