calculus anyone? (or trig?!)

[Alex]

wtf?!?!?!? :| :|

this is seriously frustrating me... i REALLY DONT GET the whole quadrant thingy for like evaluating inverse trig expressions... anyone think they can explain it to me easily?

thx!

-frangstrated (hehe)

EDIT:
evaluate:
1) arctan(tan 3pi /4)
2) cos (arcsin 1/2)
3) cos (arctan 2 + arctan 3)

if anyone has any clues?

 

[Fausto]

I'd love to help, but I long ago used a butter knife to excise the part of my brain that knew calculus.

The memories were just too painful.

 

[brunswickite]

TI-89

 

[Alex]

Originally posted by: Fausto1
I'd love to help, but I long ago used a butter knife to excise the part of my brain that knew calculus.

The memories were just too painful.

hehe ya only a few more years and i get to do that myself..

but for now....BUMP!

 

[Fausto]

Originally posted by: franguinho

Originally posted by: Fausto1
I'd love to help, but I long ago used a butter knife to excise the part of my brain that knew calculus.

The memories were just too painful.

hehe ya only a few more years and i get to do that myself..

but for now....BUMP!

I had a year of calc plus a year of Physical Chemistry (which involves a ton of very complex calc). Nearly killed me.

 

[Hammer]

Originally posted by: Fausto1
I'd love to help, but I long ago used a butter knife to excise the part of my brain that knew calculus.

The memories were just too painful.

lol my memory of it didn't last past the following semester.

course i was drinking a tad back then.

 

[Kev]

what exactly dont you understand? maybe i could dust off my brain...

 

[Alex]

yeah after im done i dare not pursue further enlightenment in calculus lest it make my quietus...

 

[Fausto]

Originally posted by: Hammer

Originally posted by: Fausto1
I'd love to help, but I long ago used a butter knife to excise the part of my brain that knew calculus.

The memories were just too painful.

lol my memory of it didn't last past the following semester.

course i was drinking a tad back then.

You? Drink a tad? :Q

/passes out from shock

 

[chin311]

NOOOOOo

/runs

i hate math, its the worst :|

 

[Alex]

Originally posted by: maladroit
what exactly dont you understand? maybe i could dust off my brain...

evauluate:
1) arctan(tan 3pi /4)
2) cos (arcsin 1/2)
3) cos (arctan 2 + arctan 3)

any clues?

 

[Turin39789]

that looks more like trig to me than calc. Calc is fun. Trig is the great darkness from the north that threatens the world of men.

 

[Alex]

trig, calc.... same sh!t different pile

 

[Fausto]

Originally posted by: franguinho
trig, calc.... same sh!t different pile

Bah. Trig is only a minor demon. Calc is the devil himself.

 

[Alex]

hehe well either way im pretty screwed then is the bottom line

 

[Fausto]

Originally posted by: franguinho
hehe well either way im pretty screwed then is the bottom line

When the going gets tough, the tough start drinking.

It is Friday after all.

 

[Alex]

hehe hmmmm i do have a couple keiths in the fridge :beer:

 

[Alex]

nothing like a nice cold beer on a summer morning ...ahhhh

 

[vtqanh]

arctan(tan 3pi/4) = arctan(tan -pi/4) = -pi/4
cos (arcsin 1/2) = cos (pi/6) = sqrt(3)/2
I haven't figured out number 3 yet

 

[vtqanh]

ok, number 3:
arctan x + arctan y = arctan ((x+y) /(1-xy))
thus, arctan 2 + arctan 3 = arctan (5/(1-6)) = arctan (-1) = -pi/4
cos (-pi/4) = cos (pi/4) = sqrt(2)/2

 

[Kyteland]

Originally posted by: franguinho

Originally posted by: maladroit
what exactly dont you understand? maybe i could dust off my brain...

evauluate:
1) arctan(tan 3pi /4)
2) cos (arcsin 1/2)
3) cos (arctan 2 + arctan 3)

any clues?

Ok, I'll try to help with the first one.

Start off by claculating the equation inside the parenthesis. tan 3pi /4. You should have this value memorized from trig tables and it is -1.

you know tan(x) = sin(x)/cos(x) so tan(3pi /4) = sin(3pi /4)/cos(3pi /4)
you know sin(3pi /4) = sqrt(2)/2 <--- trig tables anyone?
you know cos(3pi /4) = -sqrt(2)/2 <---- tables again
therefore tan(3pi /4) = -1

so now you need to finish off with the last part of the equation.
You are left with arctan(-1) = ??

arctan is the inverse tangent function. If x=arctan(y) then tan(x)=y by definition.

you have arctan(-1)=??? so by the above tan(???)=-1. Oh, but wait!!! we just calculated above that tan(3pi /4)=-1. Problem solved!!! Oops, but that values isn't defined for the range of the acrtan() function. arctan() is only defined in the range of -pi/2<arctan(x)<pi/2. Since arctan has a period of pi you subtract that from your answer above.

3pi /4 - pi = -pi/4 and that is in the proper range so it is you answer.

You can use a similar method to solve all of the rest of the questions.

 

[Alex]

vtqanh and Kyteland

you guys are the best thx so much!