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## #1 2014-05-05 05:32:10

Amrita
Member
From: Westing's House
Registered: 2014-04-30
Posts: 847

### Trig Proof Help

prove it.

In mathematics the art of proposing a question must be held of higher value than solving it.
- Georg Cantor (1845-1918)

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## #2 2014-05-05 06:36:33

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,706

### Re: Trig Proof Help

hi Amrita,

Do you know the formulas for sinX + sinY and sinX - sinY ?

Use difference of two squares and these two formulas.

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

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## #3 2014-05-05 06:56:36

Amrita
Member
From: Westing's House
Registered: 2014-04-30
Posts: 847

### Re: Trig Proof Help

can u plz tell me the  formulae?

In mathematics the art of proposing a question must be held of higher value than solving it.
- Georg Cantor (1845-1918)

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## #4 2014-05-05 07:04:11

Amrita
Member
From: Westing's House
Registered: 2014-04-30
Posts: 847

### Re: Trig Proof Help

hello bobym,how r u?talking 2 u after a long time.

In mathematics the art of proposing a question must be held of higher value than solving it.
- Georg Cantor (1845-1918)

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## #5 2014-05-05 07:10:14

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 106,389

### Re: Trig Proof Help

Hi;

Have not seen you in a few days.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
No great discovery was ever made without a bold guess.

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## #6 2014-05-05 07:14:49

Amrita
Member
From: Westing's House
Registered: 2014-04-30
Posts: 847

### Re: Trig Proof Help

actually my 1 GB net in dongle was finished.can u plz tell me the formula bob bundy was talking about?

In mathematics the art of proposing a question must be held of higher value than solving it.
- Georg Cantor (1845-1918)

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## #7 2014-05-05 07:17:33

bobbym
From: Bumpkinland
Registered: 2009-04-12
Posts: 106,389

### Re: Trig Proof Help

The only one I know offhand is:

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
No great discovery was ever made without a bold guess.

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## #8 2014-05-05 07:21:36

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,706

### Re: Trig Proof Help

That looks like the ones.

Do you want me to show where they come from?  Starting with the compound angle formulas ....
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

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## #9 2014-05-05 07:24:51

Amrita
Member
From: Westing's House
Registered: 2014-04-30
Posts: 847

### Re: Trig Proof Help

thnx. can u plz help with this sum?   if x+a is the hcf of x^2 + px +q and x^2 + lx + m,find the value of a.

In mathematics the art of proposing a question must be held of higher value than solving it.
- Georg Cantor (1845-1918)

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## #10 2014-05-05 07:26:20

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,706

### Re: Trig Proof Help

I've done this recently for someone else, maybe Agnishom??

Just looking it up.................

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

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## #11 2014-05-05 07:26:26

Amrita
Member
From: Westing's House
Registered: 2014-04-30
Posts: 847

### Re: Trig Proof Help

yes bob,u can show them.i would like 2 know it.

In mathematics the art of proposing a question must be held of higher value than solving it.
- Georg Cantor (1845-1918)

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## #12 2014-05-05 07:27:52

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,706

### Re: Trig Proof Help

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

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## #13 2014-05-05 11:57:56

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,016
Website

### Re: Trig Proof Help

bob bundy wrote:

I've done this recently for someone else, maybe Agnishom??

Just looking it up.................

Bob

Yes, you have. Because my Watari gave me this sum and I gave Amrita this sum

'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.

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## #14 2014-05-20 20:05:33

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,016
Website

### Re: Trig Proof Help

'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.

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## #15 2014-05-20 20:48:15

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,706

### Re: Trig Proof Help

hi Agnishom,

I haven't tried this yet (sound familiar ?) but this should work.

Start with (sin^2(x) + cos^2(x)) ^6 to get an expression for sin^6 + cos^6.

Use this to remove those terms from the expression.

Now do the same again with (sin^2(x) + cos^2(x)) ^4 to remove the fourth powers.

What's left will only have sin^2 and cos^2 terms so you should be able to twist it into the required result.

Hope I'm right.  :fingers crossed smiley

Bob

I'm hoping the odd powers cancel out.

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

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## #16 2014-05-20 21:04:50

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,016
Website

### Re: Trig Proof Help

Start with (sin^2(x) + cos^2(x)) ^6 to get an expression for sin^6 + cos^6.

That is tedious.

What is the fingers crossed smiley?

'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.

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## #17 2014-05-21 01:12:18

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,018

### Re: Trig Proof Help

Agnishom wrote:
bob bundy wrote:

I've done this recently for someone else, maybe Agnishom??

Just looking it up.................

Bob

Yes, you have. Because my Watari gave me this sum and I gave Amrita this sum

Watari? Like from Death Note.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #18 2014-05-21 01:15:27

ShivamS
Member
Registered: 2011-02-07
Posts: 3,648

### Re: Trig Proof Help

Agnishom wrote:

What is the fingers crossed smiley?

It is someone crossing their fingers.

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## #19 2014-05-21 01:52:27

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,016
Website

### Re: Trig Proof Help

anonimnystefy wrote:
Agnishom wrote:
bob bundy wrote:

I've done this recently for someone else, maybe Agnishom??

Just looking it up.................

Bob

Yes, you have. Because my Watari gave me this sum and I gave Amrita this sum

Watari? Like from Death Note.

Yes, I call her Watari because I call myself L

'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.

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## #20 2014-05-21 02:14:09

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,018

### Re: Trig Proof Help

Really? That's cool. I'm not sure which character I have the most in common with.

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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## #21 2014-05-21 04:57:40

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,706

### Re: Trig Proof Help

Agnishom wrote:

That is tedious.

Yes, but then again, you should have said "Have you got your glasses on Bob?  I think you meant:

and

Then start with the LHS of the required identity, multiply out the brackets, cancel some bits, factorise and use s^2 + c^2 = 1 lots of times and you'll get to

3 + 6 + 4 = 13 QED.

So get on with it!

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

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## #22 2014-05-21 14:32:09

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,016
Website

### Re: Trig Proof Help

I did it! Thank You!

'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.

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## #23 2014-05-21 18:21:07

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,706

### Re: Trig Proof Help

Excellent!

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

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## #24 2014-06-03 01:33:56

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,016
Website

### Re: Trig Proof Help

'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.

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## #25 2014-06-03 02:55:55

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,018

### Re: Trig Proof Help

Hi Agnishom

Solution

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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