Mathematics - 6 December 2007

Im looking for a proof of the derivative of the trig functions... FROM WHICH I can derive cosh x = [ e^x + e^-x ] / 2

Can anyone help with this?

The hyperbolic functions existed independent from the normal trig functions, and prior to complex analysis and their subsequently proven relationship.

Im looking for a way to prove:
cos ix = [ e^i(ix) + e^-i(ix) ] / 2 = [ e^x + e^-x ] / 2 = cosh x

... without merely defining cosh x = [ e^x + e^-x ] / 2.

My point is that how do we know cosh x = [ e^x + e^-x ] / 2 ?

cos ix = [ e^x + e^-x ] / 2... but how does that happen to be cosh also?

2007-12-06 23:50:04 · 5 answers · asked by Anonymous

point: (1,1,1)

line: x = y-1 = 2z/3

using cross product

2007-12-06 23:48:50 · 3 answers · asked by Gabriel H 3

A car drives down a road in such a way that its velocity ( in m/s) at time t (seconds) is

v(t)= 3t^(1/2)+1

Find the car's average velocity between t=1 and t-3

2007-12-06 23:38:21 · 3 answers · asked by Lauren 1

my ordered pairs don't work in graphing this linear equation.

2007-12-06 23:37:32 · 6 answers · asked by peaches 1

How do you calculate the area of a trapezoid if the units are in fractions?
Base #1: 3/4 (thats a fraction... 3 over 4)
Base #2: 1/4 (also a fraction... 1 over 4.)
Height: 1

How would you calculate the area of this trapezoid?

2007-12-06 22:48:06 · 4 answers · asked by ☮ & ♥ 6

2007-12-06 22:37:32 · 2 answers · asked by rougi a 1

i a comp science and eng undergrad. i am good at c++ and have won a few programming contests. i love mathematics and anything to do with numbers. i like thinking about solutions to problems.

2007-12-06 22:33:30 · 2 answers · asked by chicken guy 1

Evaluate the integral by interpreting it in terms of areas.

Int_(-5)^(4) (2-4x) dx

2007-12-06 22:12:25 · 1 answers · asked by Rrrr0001 1

This is not homework. If you can't give the information please don't post at all.

2007-12-06 22:02:43 · 13 answers · asked by Anonymous

please write the full answer!

2007-12-06 22:00:21 · 4 answers · asked by Peyman 2

Having trouble getting my head around this one, don't really understand what "compounded continuously" means:

Find the value at the end of 20 years of an investment of $100 which earns interest at the rate of 5% compounded continuously

2007-12-06 21:28:34 · 6 answers · asked by Anonymous

2007-12-06 21:18:17 · 7 answers · asked by sohan s 1

Find the equation of the line that passes through the points (-1,2) and (7,-2).

This is what it says in the book

Midpoint=
=(-2-2) / (7+1)
=-4 / 8
=-1 / 2

The answer is 7+2=-1/2(x-7) or y=(-1/2)x+(3/2)

So i guess i need to express it in y=mx+b
I got lost after finding midpoint -1/2. After that, where did 7+2, (x-7), and (3/2) come from? How do i find them?

2007-12-06 20:51:42 · 8 answers · asked by Mzee 3

'a' and 'b' are two real numbers such that a+b=1.

Show that:

(a+1/a)^2+(b+1/b)^2 >= 25/2

Thanks for your time and consideration.

2007-12-06 20:45:26 · 7 answers · asked by Amir 1

... and by changing the place of its digits we come to another power of 2?

Thanks for your consideration

2007-12-06 20:41:54 · 3 answers · asked by Amir 1

(1.2 x 10^13)(-3.3 x 10^-4) / 7.2 x 10^15

The question says Compute and give my answer in scientific notation.
The answer is -7.64x10^6

But i get -5.5x10^-5 ?

2007-12-06 20:26:39 · 6 answers · asked by Mzee 3

According to 1 Kings chapter 7 verse 23 it says pi=3.00 exactly. (just discovered this 2day!).Now there indeed is one in the eye for all you scientist mathematics interlectual wallas!
All this transcendental nonsense obv comes from heathen meditation stuff. We have proved science is not only ungodly and heretic (bcause it contradickts the bible) but wrong..now we can prove all the maths nonsense with its squiggly greek letters instead of real numbers heresy too. I think we should ban all maths books with stuff from pythagoras an euclid since they were heathens too. I mean even if i aint seen a right triangle with hypotenuse square sides an all doesn't mean they don't exist! If science and math was true how come we ain't all monkees still an why we have ten fingers stead of eight? Lookin for support here brother creationists!

2007-12-06 20:01:21 · 26 answers · asked by alienfiend1 3

Heres the thing.
I am baby sitting my 13 year old neice,as well as giving her tution.But there are some questions which she faced difficulty and even i could not slove.
Heres the two questions:
John bought 12 boxes of mango at $60 and each box contains x mangoes.15% of it was rotten and could not be sold.If he sells it for 25 cents each,he would make a profit of 70%,find the number of mangoes in each box.

Second Question:
A club comprising of boys and girls has a total of 160 members.If 32 more girls join the club,the percentage of girls will increase by 5%.How many boys are there in the club?

Please help as i have tried sloving the questions but to no avail.(and my neice is getting anxious)

Thanks!(please include working for the questions)

2007-12-06 19:57:56 · 8 answers · asked by ReRe_Sunshine 3

* There are 1000 micrograms in 1 milligram
* There are 1000 milligrams in 1 gram

How many micrograms in 100 grams?

PS - I am sure its pretty easy to calculate, I have worked it out, but just need to double check that my answer is correct.

Cheers!

2007-12-06 19:36:44 · 4 answers · asked by Chimera's Song 6

if you could show me how you do it step by step i would be very happy thanks

2007-12-06 19:28:32 · 7 answers · asked by Tom Jackson 1

2007-12-06 19:04:00 · 4 answers · asked by cmissypooh02 2

I thought there would be more crit numbers for this. Can
anyone help me get the right answer . Due tommorow


Find the Critical Numbers and find the max min.
Then find the second derivative

y = x+cosx



i got the first deriv as 1 - sinx or something

2007-12-06 19:03:29 · 3 answers · asked by brobo8 1

2007-12-06 19:02:54 · 4 answers · asked by cmissypooh02 2

2007-12-06 19:00:55 · 3 answers · asked by cmissypooh02 2

ESL, people... thanks! get free 10 points IF i think you're correct or something!

2007-12-06 18:48:23 · 4 answers · asked by Anonymous

The problem asks us to do the following:

Find the exact error in approximating ln[sec(0.2)] by its fourth degree Taylor polynomial at a = 0

Please show how to do this problem step-by-step.

2007-12-06 18:47:42 · 2 answers · asked by Ryan_1770 1

I have a question that reads: "A pilot wishes to maintain a ground speed of 425 mph and fly at a bearing of 155 degrees. The wind is blowing at 30 mph on a bearing of 45 degrees. Find the airspeed and bearing that the pilot should choose"

I made a vector diagram and using the law of cosines I foudn the magnitude to be 446.72 mph and the bearing to be 152.28 degrees.

If anyone could take a look at this problem and see if I've done this right I would really appreciate it!

2007-12-06 18:11:59 · 3 answers · asked by No Doubt 1

please help

2007-12-06 18:08:34 · 4 answers · asked by m.kayleigh 2

Find all points of intersection of the ellipses x^2/a^2+y^2/b^2=1 and x^2/b^2+y^2/a^2=1 where a>b.

2007-12-06 18:02:00 · 2 answers · asked by flipboi4you 1

Question:
The lines AB and CD are parallel to each other. Find the value of a in each of the cases.
(a) A (2, 3), B (4, 5) and C (4, 3), D (2, a)
(b) A (1, 2), B (3, 4) and C (-3, -2), D (a, 6)
(c) A (-1, -2), B (-5, -4) and C (1, 7), D (3, a)
(d) A (1, 1), B (a, 3) and C (-1, 4), D (2, 7)
^ Those are some of the questions I need help on.

Could you please give the fomulae and the explain the working out too?

2007-12-06 17:34:25 · 3 answers · asked by Anonymous