Math Is Fun Forum
You are not logged in.
- Topics: Active | Unanswered
#1 2014-05-05 05:32:10
- Amrita
- Member
- From: Westing's House
- Registered: 2014-04-30
- Posts: 848
Trig Proof Help
In mathematics the art of proposing a question must be held of higher value than solving it.
- Georg Cantor (1845-1918)
Offline
#2 2014-05-05 06:36:33
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
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
Sometimes I deliberately make mistakes, just to test you! …………….Bob 
Offline
#3 2014-05-05 06:56:36
- Amrita
- Member
- From: Westing's House
- Registered: 2014-04-30
- Posts: 848
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)
Offline
#4 2014-05-05 07:04:11
- Amrita
- Member
- From: Westing's House
- Registered: 2014-04-30
- Posts: 848
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)
Offline
#5 2014-05-05 07:10:14
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
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.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#6 2014-05-05 07:14:49
- Amrita
- Member
- From: Westing's House
- Registered: 2014-04-30
- Posts: 848
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)
Offline
#7 2014-05-05 07:17:33
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
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.
Always satisfy the Prime Directive of getting the right answer above all else.
Offline
#8 2014-05-05 07:21:36
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
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
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#9 2014-05-05 07:24:51
- Amrita
- Member
- From: Westing's House
- Registered: 2014-04-30
- Posts: 848
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)
Offline
#10 2014-05-05 07:26:20
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
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
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#11 2014-05-05 07:26:26
- Amrita
- Member
- From: Westing's House
- Registered: 2014-04-30
- Posts: 848
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)
Offline
#12 2014-05-05 07:27:52
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
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
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#13 2014-05-05 11:57:56
Re: Trig Proof Help
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.
Offline
#14 2014-05-20 20:05:33
Re: Trig Proof Help
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'
I'm not crazy, my mother had me tested.
Offline
#15 2014-05-20 20:48:15
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
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
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#16 2014-05-20 21:04:50
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.
Offline
#17 2014-05-21 01:12:18
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
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
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.
Offline
#18 2014-05-21 01:15:27
- ShivamS
- Member
- Registered: 2011-02-07
- Posts: 3,648
Re: Trig Proof Help
What is the fingers crossed smiley?
It is someone crossing their fingers.
Offline
#19 2014-05-21 01:52:27
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.
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.
Offline
#20 2014-05-21 02:14:09
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
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.
Offline
#21 2014-05-21 04:57:40
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
Re: Trig Proof Help
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
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#22 2014-05-21 14:32:09
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.
Offline
#23 2014-05-21 18:21:07
- Bob
- Administrator
- Registered: 2010-06-20
- Posts: 10,621
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
Sometimes I deliberately make mistakes, just to test you! …………….Bob
Offline
#24 2014-06-03 01:33:56
Re: Trig Proof Help
Please help me with proving
'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
#25 2014-06-03 02:55:55
- anonimnystefy
- Real Member
- From: Harlan's World
- Registered: 2011-05-23
- Posts: 16,049
Re: Trig Proof Help
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.
Offline