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**Amrita****Member**- From: Westing's House
- Registered: 2014-04-30
- Posts: 816

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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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

hi Amrita,

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

Use difference of two squares and these two formulas.

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**Amrita****Member**- From: Westing's House
- Registered: 2014-04-30
- Posts: 816

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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**Amrita****Member**- From: Westing's House
- Registered: 2014-04-30
- Posts: 816

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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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 92,921

Hi;

Have not seen you in a few days.

**In mathematics, you don't understand things. You just get used to them.**

**I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.**

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**Amrita****Member**- From: Westing's House
- Registered: 2014-04-30
- Posts: 816

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

- Georg Cantor (1845-1918)

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 92,921

The only one I know offhand is:

**In mathematics, you don't understand things. You just get used to them.**

**I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.**

**Online**

**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

That looks like the ones.

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

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**Amrita****Member**- From: Westing's House
- Registered: 2014-04-30
- Posts: 816

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.

- Georg Cantor (1845-1918)

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

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

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

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**Amrita****Member**- From: Westing's House
- Registered: 2014-04-30
- Posts: 816

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

- Georg Cantor (1845-1918)

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

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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'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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Please help me with proving this:

'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'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

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.

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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'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,889

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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**ShivamS****Member**- Registered: 2011-02-07
- Posts: 3,640

Agnishom wrote:

What is the fingers crossed smiley?

It is someone crossing their fingers.

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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

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,889

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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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

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

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I did it! Thank You!

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,787

Excellent!

Bob

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Please help me with proving

'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'

'You have made another human being happy. There is no greater accomplishment.' -bobbym

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**anonimnystefy****Real Member**- From: The Foundation
- Registered: 2011-05-23
- Posts: 15,889

Hi Agnishom

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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