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#1 2019-05-24 11:15:25

Jaspers
Member
Registered: 2019-05-24
Posts: 54

tan(18°)

Without using a calculator, prove that

No calculators, please. Well, you can’t use a calculator anyway; that value is irrational so a calculator won’t give you the exact result.


Reason is like an open secret that can become known to anyone at any time; it is the quiet space into which everyone can enter through his own thought.

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#2 2019-05-24 23:11:39

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 45,956

Re: tan(18°)

Hi,

Are you posting a puzzle? You ought to post in 'Games and Puzzles' topic, not 'Help me' topic.


It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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#3 2019-05-24 23:17:16

Jaspers
Member
Registered: 2019-05-24
Posts: 54

Re: tan(18°)

Can you move this thread to that section? Thanks.


Reason is like an open secret that can become known to anyone at any time; it is the quiet space into which everyone can enter through his own thought.

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#4 2019-05-25 23:27:54

Bob
Administrator
Registered: 2010-06-20
Posts: 10,053

Re: tan(18°)

hi Jaspers

Welcome to the forum.

Nice problem.  Had an idea but kept messing up the algebra.  Here's my final version:

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 smile

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#5 2019-05-26 04:42:49

Jaspers
Member
Registered: 2019-05-24
Posts: 54

Re: tan(18°)

Thanks Bob!

My solution is entirely non-geometric.


Reason is like an open secret that can become known to anyone at any time; it is the quiet space into which everyone can enter through his own thought.

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