Scribe Post 10/1/10

https://docs0.google.com/document/d/1lifUs_-b3c2aoNERQQKVsFh5y1C6iyUjJRJ65fZYAtg/edit#

5/5 Scribe Post

Today we started with a warm up involving vectors. The first question was to find the component form, magnitude, and direction angle for vector AB and CD, with given points A(1,1) B(4,-1) C(-5,3) D(-2,1) .
The component form of both the vectors was <3,-2> and the magnitude was . To find the direction angle you create an axis with the initial point as the vertex. The direction angle is then measured counter clock wise. The direction angle is then,, so the two vectors AB and CD are equal. This means that two vectors with the same component form are equal to each other.
Mr. O'Brien showed us the formula to find the component form:
Terminal Point - Initial Point. After this warm up problem we went over problem 59 from the homework. We found out that the component form can be found by , usin> where u was 7/2 for problem 59.


The second warm up question: given u = <2,1> and v = <-1,4>
a. find 3u
b. Graph u and 3u on Geogebra, What do you notice?
c. Repeat a. and b. for u + v
d. Repeat a. and b. for u-v
For this problem we discovered that vector addition is done "tip to tail". So when vector u, vector v and vector u+v are combined they form a triangle. When a vector is multiplied by a number, it is a called a "Scalar multiplication" and it lengthens or shortens the vector.
ex. <3,4> to make a unit vector in the same direction:

Quiz:
After we completed the warm up we discussed the upcoming quizes and tests and decided to review the warm up at the end of class. Next we reviewed the quiz we took last class. Mr. Obrien showed us how to solve problem 1 on the quiz using a calculator only, but wanted to make sure that we could do this problem without a calculator using the sum and difference identity. To solve problem 1 you need to use the sum and difference formulas, then cancel and simply the equation. For problem 2 from the quiz Mr. Obrien recommended that we draw the triangles to start this type of problem. Problems 1 and 2 could both appear on a non-calculator section of a test. Problem 3 you needed to use factoring then an identity to simplify the expression. On problem 4 you needed to remember that there were two answers, . Problems 5 involved using the Area of a triangle formula, A = 1/2 b x h or for this certain problem, A = 1/2 cbsinA. For problems 6 and 7 most people didn't have problems using the double angle formulas and the Law of Sines. The last problem, #8 gave people more trouble. It is important to use the correct fundamental identites.

Scribe Post 1/8/10

At the beginning of class people had questions with the homework problems at the end of the assignment using the sum of the first n terms of any arithmetic sequence formula, #67, 69, 71, 85. We started with the warm-up which was doing the half-sheet of arithmetic sequences and series which was passed out to us last class. Mr. Obrien explained how make a table with arithmetic sequences to find the common difference. The graph of a arithmetic sequence has a linear graph, y = mx + b. He also reminded us to always check our answers for n by simply testing it.

Mr. Obrien showed how to solve the nth term without using the formulas, which was much quicker. For example:,, 9d + = , 9d + 16 = 43, 9d = 27, d = 3. So instead of using formulas you can find without them. = 3n + 4. Because 3 is the difference so it is the nth term, then since you know = 16, 4 x 3 = 12 + 4 = 16, so you found the nth term without using the formula.

We learned about Gauss's formula of finding how to find the sum of numbers 1 through 1000. So 1001 x 500 = 500500. The formula for this is: .

Next students put up the answers to the questions from the homework that students had questions on. Mr. Obrien explained that there are three numbers between 10 and 12, 10, 11, 12. This sounds simply, but it is helpful to understand when doing problems such as #69 on the homework. Next he passed out a yellow half-sheet. We started by defining a geometric sequence:
= r x
To finish class we filled in the formulas on the yellow sheet which we will use for tonights homework.

HWK assigned10/18

I had trouble on problems p.134/23 ,79, p.149/21, 29, 33, 41. I forgot how to put parabolas in standard form and also forgot what a and b are in the equation for the axis of symmetry.
-Henry W-2

Scribe Post for 9/21/09

We took the test for the first thirty minutes. People had questions on p.71/31, p.71/53, 55, 56, p.79/65, p.79/31b and d. People also had question on 53-60 on how to write the new equation. The concepts of these problems are what most people seemed to need instruction on. Also as I said on my other post, I don't understand how to put the equation into words. Some people had trouble finishing the classwork in class. People also had trouble figuring out the parabola equations.

Homework for 9/15

Could we go over problems p.49/89 and p.63/47. I got an answer, but I would like to review them. Also I could use a quick review on graphing calcs. Tyler from my W-2 class gave me a good overview on how to use them on the homework problems, but I don't know how to use them for other types of problems.
Thank you,
Henry W-2