## Thursday, October 30, 2008

### Slides October 30

Apologies for the delay, I hope you still get to see this before the test.

PreCal 20S October 30

### Cosine Law

Today what we did was Exercise 25 # 1-9 , 17 ,18.

1.) a^2 = 15,b^2= 19, < c =" 50" 2=" a" c =" 15^2" 39 =" 586" 39 =" 219.61" a ="15," b =" 10," c =" 12."> A to the nearest degree.

a^2 = b^2 + c^2 - 2bc cos A
a^2 -b^2-c^2 = 2bc cos A
(a^2 -b^2-c^2)/2bc = cos A
A = cos-1 [(a^2 -b^2-c^2)/2bc )]
A = cos-1 [(15^2 - 10^2 - 12^2)/2(10)(12)]
A = 85 degrees

9.a) Find the area of the triangle.

c^2 = a^2 + b^2
c^2 - b^2 = a^2
10^2 - 6^2 = a^2
100 - 36 = a^2
64 = a^2
a = 8
a = h
h=8

A = bh/2
A = (12)(8)/2
A = 48 units^2

9.b) If you know the lengths of all three sides of an isosceles triangle, you have to use the pythagorean theorem to find the height of the triangle. Once you find the height, you can plug in the values to the formula and you can find the area.

17. Does the line 2x + 3y = 39 pass through the point (9, 7)? Justify.

2x + 3y = 39
3y = -2x + 39
y = (-2/3)x + 13

y = (-2/3)(9) + 13
y = -6 + 13
y = 7

18. Draw a diagram to show Triangle ABC if AB = 8, AC = 12, and angle A = 55 degrees. Find the area of the triangle.

A = [bc(sin A)]/2
A = [(12)(8)(sin 55)]/2
A = 39.3 units^2

THE NEXT SCRIBE WILL BE............................
POGIshawn

## Tuesday, October 28, 2008

### Pre-Test and Test Trig

Pre-test will be October 30th

Test on October 31st

Everything we did in the TRIG unit

Exercise 25 1-7, 9, 17, 18 is on the Cosine Law, DO IT!

Possibly some stuff from previous units, but not much

You don't have to study on Halloween

Do the assignment, it will help!

## Monday, October 27, 2008

### Slides Oct 27

Here they are ....

Pre Cal20 S Oct27

## Friday, October 24, 2008

### Ɍȉǵħť Ŧŕĩăńģłėś

Alright... Time To Blog...

During class, Dr. Eviatar did some things about right triangles. So I think that's what i'm putting here. Just notify me if there's something wrong. So good luck guys and take a look at it!! :P

So Let's see.... Here's the one she did.

SIN A/a = SIN B/b = SIN C/c

Angle B = 72°

Angle C = 67°

b = 42

c = ?

b/SIN B = c/SIN C

42/SIN 72̲̲̲̲̱̱̱̱̲̲̲̲̱̱̱̱° = C/SIN 67°

(42) (SIN67°/SIN72°)

So it will be...

(42)(SIN67°) = 36.5

After that... Do this like :

36.5/SIN72°

c = 40.3

There you have it.

Oh,, Finally... I almost forgot, there's a homework that Mrs. Eviatar wants us to finish.

Homework (Exercise 19 # 2-6, 17)

2.

Find The Value of X.

3.

Find b.

4.

Find a.

5.

Find Angle A.

6.

Find Angle B .

17. The school flagpole is 14m high. A student measures the angle of elevation of the top of the pole to be 31°. She then moves closer to the pole and finds the angle of elevation has increased to 48°. Find the distance that she moved from the first measurement to the second.

___________________________________________________

Alright!! Finally I'm done.... Take a look at those and check if there's something wrong... Good luck to all of you guys!!.. :)

SO I THINK THE NEXT BLOGGER WILL BE AKEEM NOW!!!

YOUR THE ONE WHO'S NEXT HAHAHAHAH!! :P

HOPE YOU DO IT!!

### Slides October 24th

Here they are ...

Pre Cal20 S Oct24

## Thursday, October 23, 2008

OMG!!!
What an empty blog...
No one was blogging so Dr. Eviatar asked me to do a post.
I wasn't paying much attention last class because I'm feeling lazy. Anyways, she helped us with some of the questions on Exercise 17: Trigonometry. I didn't remember how she do it, so i tried it on my own, please take a look and just blame me for any errors.

4.
BD-BC=CD

BD

Tan 38= 40/A
A= 40/Tan 38

BC

Tan 52= 40/A

A= 40/Tan 52

BD- BC= CD
51.2-31.4=CD 19.8= CD

5.

<EDC=?

BE

Tan 20= O/8
Tan 20 (8)= O
2.91= Opposite

BC- BE= EC
6- 2.91= 3.09

Tan <EDC= O/A
Tan <EDC= 3.09/8
Tan <EDC= 0.386= 21.1 degrees

Finish finally.
I'm not sure who haven't blog yet so I'll let Dr. Eviatar to pick the next blog.
T.Y. for viewing I guess.

### Scribe List

People whose names have been crossed out have blogged and will receive that 5% of your mark which depends on your participation in this blog.

If you are not one of these people, please ensure that you join that select group SOON.

POGIshawn .
Arvee A
rowenaa
ana soria
franny
jesnicz
Arjel H
kimberly
kris?!
mark e.
jAnDaCanAy;
caseyh
Jessica.T :3
ICON
Jeyson
DILA
faven
YaSSin
Levi
* Akeem
ChemutaiB

## Monday, October 20, 2008

### Slides October 20

Here they are ....

Pre Cal20 S Oct20

## Thursday, October 16, 2008

### Slides October 16th (Pre-Test)

Here they are ....

Pre Cal20 S Pre Test Ag

### Slides October 14th

Here they are ....

Pre Cal20 S Oct14

## Friday, October 10, 2008

### Slides October 9th

Here they are ....

Pre-Cal 20S October 9th, 2008

## Tuesday, October 7, 2008

### Yassir's post

Hi class
Today we did quiz about geometric. It was three question out of ten marks. I couldn't get the first two question specially question one .Because we had to find the value of k that why it was harder then the other two question. When we finished the quiz, we switch the paper to our partner, and we corrected together. I try my best to get this mark, and am proud of it the mark i get it. The next time i will work harder then i did this time.
that's all i can say thank you!

The next Blog will be Feven

## Monday, October 6, 2008

### Slides October 6th

Here they are ....

Pre-Cal 20S October 6th, 2008

## Sunday, October 5, 2008

### GRAPHING LINES-(USING INTERCEPTS)

When graphing lines using slope you should always remember one very important thing and that is,
for every line on x there is a y value of 0 and for every line of y there is an x value of 0.
That would look something like this, x=y=0 while y=x=0.

If you had a question like y=4x+4 you would follow this steps to solving it;

Step 1: remind yourself that for the x-int y=0.

Step 2: Put a 0 for the y value like this y(0)=4x+4

Step 3: Finish working it out, so 0=4x+4

Step 4: Subtract 4 from both sides in order to have your x value isolated.

Do the same thing to find the y int. but *remember to put a 0 for the x value*.

Your y value will be 4.

YOU HAVE SUCCESSFULLY FOUND YOUR X AND Y INTERCEPTS.
x is (-1,0)
y is (0,4)

(-1,0)(0,4)

Last Step: Graph your intercepts on the Coordinate plate and you are done!!

That was question 1 from exercise 12.

The next scribe will be......YASSIR.

## Friday, October 3, 2008

### Slides October 3rd

Here they are ... have a good weekend!

Pre-Cal 20S October 3rd, 2008

## Thursday, October 2, 2008

### Graphing lines intercept

hi! everyone I'm your scribe today. Dr. Aviatar discussed about intercept she did some example for us as a class. Most of her explanation was about intercepting X is always Y=0, Intercepting Y is always X=0.

This is one of Dr. Aviatar's example:
3x-2y=6

x-intercept
y=0

3(x)-2(0)=6
3x=6
x=2

y-intercept
x=0

3(0)-2(y)=6
-2y=6
y=-3

Dr. Aviatar gave us seat work its on the book Exercise 11 (#1,3,5,7&9)
for the homework part is also on Exercise 11 (#11-13-line segment)
By the way the next scribe for tomorrow's class will be Faven....

### Slides September 30th

Here are Mrs. Karras's slides from September 30th. If you want the ones from October 1st, drop me a note.

### Slides October 2nd

Here they are. Mrs. Karras's files to follow.

Pre-Cal 20S October 2nd, 2008

## Wednesday, October 1, 2008

Today, most of the students were away on a field trip so we got to do whatever we wanted so there weren't any notes or assigned homework for today.

All we did with the teacher today was go through question 5 from yesterdays homework.

Exercise 6 : Question 5

y = 3x-2y = 6
= 3(1)-2y = 6
= 3-2y = 6
= -3 -3
= -2y/-2 = 3/-2
y = -1.5

Tomorrows scribe is.. ana

pcEz