Math Is Fun Forum
You are not logged in.
- Topics: Active | Unanswered
Pages: 1
#1 2014-06-29 01:59:40
Area by Integration
I've three functions: f(x), g(x) and h(x). How do I find the area they enclose?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#2 2014-06-29 02:38:21
- ElainaVW
- Member
- Registered: 2013-04-29
- Posts: 580
Re: Area by Integration
Hello:
I guess that a question phrased like that would get many down votes at the SE.
Offline
#3 2014-06-29 03:16:24
Re: Area by Integration
But this is not SE! 
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#4 2014-06-29 04:15:39
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Area by Integration
Sketch them (good practice for any integration anyway). Then find where they intersect. Then adopt a strategy for getting the area you want.
Bob
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#5 2014-06-29 04:42:52
Re: Area by Integration
So, there is no magical formula?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#6 2014-06-29 17:57:40
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Area by Integration
Is the simplest idea for between two functions provided f(x) is the function on top.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#7 2014-06-29 19:15:50
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Area by Integration
hi Agnishom,
These three functions may show you the difficulty coming up with a single formula.
1 is sin(x)
2 is 2sin(x)
3 is (x-1.5)^2
The enclosed area would be
difference between 2 and 3 in the region a to b
difference between 2 and 1 in the region b to c
difference between 2 and 3 in the region c to d.
Until you know those crossing points you cannot decide the values of a, b, c and d.
And a small change in one function would change everything.
Bob
Last edited by Bob (2014-06-29 19:19:07)
Children are not defined by school ...........The Fonz
You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#8 2014-07-10 23:27:29
Re: Area by Integration
Okay. So what should have been my question?
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#9 2014-07-10 23:28:54
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Area by Integration
Post a problem.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#10 2014-07-10 23:37:02
Re: Area by Integration
I do not have any
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#11 2014-07-10 23:39:12
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Area by Integration
What inspired the original question?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#12 2014-07-11 01:05:59
Re: Area by Integration
The rhombus area problem
'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.
Offline
#13 2014-07-11 01:12:25
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Area by Integration
I am sorry, I do not remember it.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#14 2014-09-02 09:23:14
- αβγ
- Member
- Registered: 2014-09-02
- Posts: 19
Re: Area by Integration
You can't really use a magical formula to obtain the answer easy peasy because you have 3 functions, each with their own graph. Since I don't know how the graphs are oriented and how they intersect, the only actual answer without anymore information would be the sum of the negative or positive of each integral of each function, i.e.:
That's the most precise answer (in reduced form) that can be obtained without further information.
α as in alpha stands for "a love of math"
β as in beta stands for "being skilled in the latter"
γ as in gamma stands for "getting sick of homework"
Offline
Pages: 1