John's Scribepost for December 5th,2010

Sup guys today in class we talked about scale and scale factors.
The first thing we did was this:

Scale : Proportional Reasoning

Image : Actual

Then we did a problem is was:

A B Aprime Bprime
1 : 7 X : 23.5

But before starting with the question Mr.Backe
explained something about where the primes should go and where they shouldn't go.

Works: A/Aprime = B/Bprime

Doesn't Work: A/Aprime = Bprime/A

Then we started on the question

1 : 7 x : 23.5

1/x = 7/23.5 so you would cross multiply the numbers so 7 multiply x equals 7x
so you would put it like this.

7x/7 = 23.5/7 then 7x/7 would cancel each other out so you would divide 23.5 by 7 and your answer will be 3.36
X=3.36

After we were done talking about that question we did another

2 : 3 11 : x

2/3 = 11/x so as the last question went you would multiply 2 by x which would equal 2x and 3 by 11 which would equal 33. So the format would be like this

2x/2 = 33/2

2x/2 would cancel each other out and you have to divide 33 by 2 to get your answer of 16.5.
X=16.5 Mr.Backe said it was called By Inspection.

After finishing more questions we reviewed the

mm cm dm dam hm km
mi ci di 1000 deca heca kilo
1000000 10000 m 100 10 1
100000 l
g

Then Mr.Backe asked how many 1cm would you need to reach 10km and the answer was you would need 100000 1cm to get the 10km.

Then Class Ended.

Homework:
Read 4.2 139-142
do SYK
CYU 1-3
Practise: odd or even
Apply: 13-16 or 15-19
Extend: 20 and 21 or 21 and 22 (you have to do 21 for sure)

TEST ON WENSDAY ON SCALE AND SCALE FACTOR

If I got anything wrong tell me so I can fix it!!!

JOHN!

Ezekiel's Scribe Post for October 7th, 2010

Today in math Mr. Backe showed us how to do our homework that we had to do.

The Answer:
Whole Shape
S.A. = 2(L) (W) + 2(L) (H) + 2(W) (H)
S.A. = 2(12) (5) + 2(12) (10) + 2(10) (5)
S.A. = 120+240+100
S.A. = 460 u ²
Hole Taken out
S.A. = 2(L) (W) + 2(L) (H) + 2(W) (H)
S.A .= 2(4) (5) + 2(4) (6) + 2(5) (6)
S.A. = 40+48+60
S.A. = 148 u ²
Faces Taken Out
S.A. = 2(LH)
S.A. = 2(4x6)
S.A. = 48
Total Surface Area
S.A. = 460+148-48
T.S.A. = 560 u ²
Mr. Backe asked us if we understood how to do surface area. Some of us didn't understand so he gave us another question. He told us we could do it on our own if we wanted. I did it on my own

The Answer:
Whole Shape
S.A. = 2(L) (W) + 2(L) (H) + 2(W) (H)
S.A. = 2(7) (8) + 2(7) (9) + 2(8) (9)
S.A. = 112+126+144
S.A. = 382 u ²
inside the hole
S.A. = 2(L) (W) + 2(L) (H) + 2(W) (H)
S.A. = 2(3) (8) + 2(3) (4) + 2(8) (4)
S.A. = 48+24+64
S.A. = 136 u ²
Faces Taken off
S.A. = 2(LH)
S.A. = 2(3 x 4)
S.A. = 24 u ²
Total Surface Area
S.A. = 382+136-24
T.S.A = 494 u ²

When everybody understood how to do the cube Mr.Backe showed asked us if we remembered how to find the circumference of a circle.
Circumference formula's: 2╥r or ╥d

Then he told us the formula for a cylinder
2╥rh+2╥r²
Then he gave us a cylinder that we were gonna do together.


Mr.Backe asked us how to find the radius from the diameter
r = d/2
r = 6/2
r = 3 cm
then he asked us to make a net of the cylinder

now we can solve the cylinders surface area
S.A. = 2╥rh+2╥r²
S.A. = 2╥(3) (12) + 2╥(3²)
S.A. = 229.19+56.55
S.A. = 282.74 cm²

I didn't put the first cylinder that we did together so.
r=d/2
r=10/2
r=5
S.A. = 2╥rh+2╥r²
S.A. = 2╥(5) (20)+2╥(5²)
S.A. = 628.32+157.08
S.A. = 785.4 cm ²
Remember for homework was in apply questions 13, 14, and 15 and Tutpup everyday


Also I pick Karra for the next scribe post. Have fun >:D