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## #1 2014-05-04 03:40:37

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,835
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### Trig - Compound Angles

Prove that

tan 8θ - tan 6θ - tan 2θ = (tan 8θ)(tan 6θ)(tan 2θ)

'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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## #2 2014-05-04 03:57:28

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,835
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### Re: Trig - Compound Angles

Proof

Last edited by Agnishom (2014-05-04 22:20:19)

'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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## #3 2014-05-04 08:19:56

bob bundy
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Registered: 2010-06-20
Posts: 8,108

### Re: Trig - Compound Angles

hi Agnishom,

Nice solution!    But check line 5 out of 6.

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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## #4 2014-05-04 13:25:23

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

### Re: Trig - Compound Angles

Agnishom wrote:

Prove that

tan 8θ - tan 6θ - tan 2θ = (tan 8θ)(tan 6θ)(tan 2θ)

I haven't looked at your proof, but here's what I would do:

tan8θ - tan6θ - tan2θ
= tan8θ-(tan6θ + tan2θ)
= tan8θ - tan(6θ + 2θ)(1 - tan6θ * tan2θ)
= tan8θ - tan8θ * (1 - tan6θ * tan2θ)
= tan8θ(1 - 1 + tan6θ * tan2θ)
= tan8θ * tan6θ * tan2θ

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## #5 2014-05-04 22:20:55

Agnishom
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From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,835
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### Re: Trig - Compound Angles

Fixed it, Bob

Shivam, That is the same thing I've done. Thanks for helping, though.

'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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## #6 2014-05-05 01:02:14

bob bundy
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Registered: 2010-06-20
Posts: 8,108

### Re: Trig - Compound Angles

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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