## Tuesday, March 31, 2009

### BOB, Show Some Identification Please :D

Since our test is on Wednesday I've decided to BOB already. I know what some of you may be thinking... "It's Spring Break! Have fun! It's to early for a BOB!" But you know what ? I have lots of work and I might as well get this over with. >__<

I understand this topic. I really do. My quiz may state otherwise but I UNDERSTAND. I swear! It's just that I don't have many clever ideas and that I tend to do things the long way. I guess this means I have to study.. lots. :(

Well I guess this is basically what we need to know for this unit:

1. Work with the complicated side of the identity first.

2. Rewrite both sides of the identity in the terms of sine and cosine.

3. Use a Pythagorean identity to make a substitution (sin^2x + cos^2x = 1, 1 + cot^2x = csc^2x, sec^2x + 1 = tan^2x ). So if you have 1 - sin^2x for example, substitute i
t with cos^2x.

4. Simplify complex fractions or rewrite fractions of sums and differences with the same common denominator.

5. Factor (especially use difference of squares).

Oh wait I lied... there is ONE rule: NEVER EVER CROSS THE GREAT WALL OF CHINA !!

Then there are sum and difference identities...

sin(a+b) = sinacosb + cosasinb
sin(a -b) = sinacosb - cosasinb
cos(a+b) = cosacosb - sinasinb
cos(a-b) = cosacosb + sinasinb

Use them :D

Just substitute the values of a and b. Then evaluate. You might have to find out what the angles are but you guys are all geniuses ;)

Oh and then there are those double identities. Look those over because we are most likely going to need them :)

I guess that's it... well that was short :D

I just noticed that I use smiley faces a lot. :O