Calling all GEEKS-CALC HELP NEEDED PLEASE!!!!!!!!!

BHAkeet00 · Post by **BHAkeet00** » April 8, 2008 11:11 pm

I have one homework problem that i don't know what to do next. PTG figured there was someone on BN that would be able to figure it out. here goes

(tan x/csc x) = sec x-cos x

Notes will be given upon request.

you are only allowed to change one side to equal the other side. and it has to deal with substituting. GOOD LUCK and THANKS!

Becca

surfpirate · Post by **surfpirate** » April 8, 2008 11:23 pm

(tan x/csc x) = sec x-cos x

tan x = sin x / cos x
csc x = 1 / sin x
sec x = 1/cos x

(tan x csc x) / (sec x)

= (sin x / cos x) (1/sin x) / (1/cos x)

= (sin x / cos x) (1/sin x) (cos x / 1)

= (sin x / cos x) (cos x / sin x)

= (sin x cos x) / (cos x sin x)

= (sin x cos x) / (sin x cos x)

= 1

wait ? you said sec x-cos x, right?

Never mind.

Post by **SMLCHNG** » April 8, 2008 11:23 pm

Can't help, sorry..

This is another reason I think the alphabet should not be combined with mathematics..

I mean, really, does grammar and English incorporate numbers for their lessons ?

(tan x/csc x) = sec x-cos x
I see a tan being worked on and The SEC vs. a team from Colorado Springs.

Sorry Becca.... no help here.

springparrot · Post by **springparrot** » April 8, 2008 11:25 pm

SMLCHNG wrote:Can't help, sorry..

This is another reason I think the alphabet should not be combined with mathematics..

I mean, really, does grammar and English incorporate numbers for their lessons ?

(tan x/csc x) = sec x-cos x
I see a tan being worked on and The SEC vs. a team from Colorado Springs.

Sorry Becca.... no help here.

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 8, 2008 11:27 pm

so much for my two trig and five calculus courses....

pojo · Post by **pojo** » April 8, 2008 11:38 pm

I can't remember that

and I love math.

PalmTreeGal · Post by **PalmTreeGal** » April 8, 2008 11:42 pm

surfpirate wrote:(tan x/csc x) = sec x-cos x

tan x = sin x / cos x
csc x = 1 / sin x
sec x = 1/cos x

(tan x csc x) / (sec x)

= (sin x / cos x) (1/sin x) / (1/cos x)

= (sin x / cos x) (1/sin x) (cos x / 1)

= (sin x / cos x) (cos x / sin x)

= (sin x cos x) / (cos x sin x)

= (sin x cos x) / (sin x cos x)

= 1

wait ? you said sec x-cos x, right?

Never mind.

Message from Becca (via PalmTreeGal): Thanks for the help. I don't think it's supposed to = 1. The way that the teacher explained it to me is that each side is supposed to = each other and you can only make changes to one side of the =. He said also that it's supposed to work no matter which side of the = you change. Becca has tried working with both sides and no luck yet.

surfpirate · Post by **surfpirate** » April 8, 2008 11:48 pm

PalmTreeGal wrote:
surfpirate wrote:(tan x/csc x) = sec x-cos x

tan x = sin x / cos x
csc x = 1 / sin x
sec x = 1/cos x

(tan x csc x) / (sec x)

= (sin x / cos x) (1/sin x) / (1/cos x)

= (sin x / cos x) (1/sin x) (cos x / 1)

= (sin x / cos x) (cos x / sin x)

= (sin x cos x) / (cos x sin x)

= (sin x cos x) / (sin x cos x)

= 1

wait ? you said sec x-cos x, right?

Never mind.
Message from Becca (via PalmTreeGal): Thanks for the help. I don't think it's supposed to = 1. The way that the teacher explained it to me is that each side is supposed to = each other and you can only make changes to one side of the =. He said also that it's supposed to work no matter which side of the = you change. Becca has tried working with both sides and no luck yet.

I was being a wise@__

(sorry).

Now I feel obligated to give this a shot ....... this may take a while ......

chippewa · Post by **chippewa** » April 8, 2008 11:50 pm

I can't help but Yahoo Answers has some similar problems and answers there.

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:10 am

math sux.... no, really.....

I don't understand what the teacher is looking for....

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:14 am

By George, I think I've got it!

1=1....

gimme a second and I'll type it all in...

PalmTreeGal · Post by **PalmTreeGal** » April 9, 2008 12:15 am

Neither do I. She brought this to me in hopes that I might be able to figure it out and well, you can probably guess, I didn't. I thought maybe, just maybe, SOMEONE from BN might know.

It was worth a shot. She still has time but it is due tomorrow. Maybe someone can post some help later on tonight.

thanks everyone! If anyone else has any ideas, please bring them on!

surfpirate · Post by **surfpirate** » April 9, 2008 12:15 am

SchoolGirlHeart wrote:math sux.... no, really.....

I don't understand what the teacher is looking for....

Using substitution, convert:

(tan x/csc x) so that it becomes (equals) sec x-cos x

or convert

sec x-cos x so that it becomes (tan x/csc x)

So that the end of your proof will be either:

(tan x/csc x) = (tan x/csc x)

or

sec x-cos x = sec x-cos x

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:23 am

(where you see sin2x or cos2x that's sin (squared) x or cos (squared) x

(tan x/csc x) = sec x-cos x

(tan x/(1/sin x)) = sec x-cos x

(tan x)(sin x) = sec x-cos x

(sin x/cos x)(sin x) = sec x-cos x

(sin2 x)/(cos x) = sec x-cos x

sin2x = (sec x)(cos x) - (cos x)(cos x)

sin 2x = (1/cos x)(cos x) - cos2x

sin2x = 1 - cos2x

sin 2x + cos2x = 1

1 = 1

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:25 am

surfpirate wrote:
SchoolGirlHeart wrote:math sux.... no, really.....

I don't understand what the teacher is looking for....
Using substitution, convert:

(tan x/csc x) so that it becomes (equals) sec x-cos x

or convert

sec x-cos x so that it becomes (tan x/csc x)

So that the end of your proof will be either:

(tan x/csc x) = (tan x/csc x)

or

sec x-cos x = sec x-cos x

That's what I thought but it doesn't make sense to me. However, you can get 1=1 but you have to work both sides, and it sounds like that's not what the teacher wants....

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:28 am

wait, I *DO* have it!!

surfpirate · Post by **surfpirate** » April 9, 2008 12:30 am

SchoolGirlHeart wrote:wait, I *DO* have it!!

Yes you do. Great job.

But I think the teacher wants only one side worked at a time so that it equals the other side unchanged. Take your proof calculations and manipulate only one side and you've got it!

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:30 am

(where you see sin2x or cos2x that's sin (squared) x or cos (squared) x

(tan x/csc x) = sec x-cos x

(tan x/(1/sin x)) = sec x-cos x

(tan x)(sin x) = sec x-cos x

(sin x/cos x)(sin x) = sec x-cos x

(sin2x)/(cos x) = sec x-cos x

(1-cos2x)/(cos x) = sec x-cos x

1/cos x - cos2x/cosx = sec x-cos x

1/cos x - cos x = sec x-cos x

sec x - cos x = sec x-cos x

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:31 am

surfpirate wrote:
SchoolGirlHeart wrote:wait, I *DO* have it!!
Yes you do. Great job.

But I think the teacher wants only one side worked at a time so that it equals the other side unchanged. Take your proof calculations and manipulate only one side and you've got it!

Yep, halfway down I just had to keep substituting.

OMG, I can still do trig....

SchoolGirlHeart · Post by **SchoolGirlHeart** » April 9, 2008 12:37 am

Trig was the only math I ever really liked and I think it's because it's more words (letters) than numbers...