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  #21  
Old 28-05-2010, 09:02 PM
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renormalised (Carl)
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The hypotenuse is the side of the triangle which is the longest...e.g. think of a right angled triangle...the two lines which are at right angles to one another, are the adjacent and opposite lines. The line running between to two ends of those lines is the hypotenuse.
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  #22  
Old 28-05-2010, 09:05 PM
beefking (Nathan)
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hypotamoose
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  #23  
Old 28-05-2010, 09:44 PM
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Quote:
Originally Posted by renormalised View Post
The hypotenuse is the side of the triangle which is the longest...e.g. think of a right angled triangle...the two lines which are at right angles to one another, are the adjacent and opposite lines. The line running between to two ends of those lines is the hypotenuse.

"
Once upon a time in an Indian village, there lived three squaws. Two squaws had young sons who were very overweight. The first squaw, whose son weighed 150 pounds, always placed her son on a bear hide near a pine grove; the second squaw, whose son also weighed 150 pounds, put her son on a moose hide in the shade of a large oak tree; but the third squaw, who was expecting the birth of her first son, always rested on a hippopotamus hide beside a bubbling brook. Her weight? 300 pounds! To this day, mathematicians give credit to these women and their children for proving the Pythagorean Theorem, because you see: The squaw of the hippopotamus is equal to the sons of the squaws of the other two hides."

This version taken from http://www.trottermath.net/humor/jokes.html
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  #24  
Old 28-05-2010, 09:50 PM
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Originally Posted by beefking View Post
Quote:
"Once upon a time in an Indian village, there lived three squaws. Two squaws had young sons who were very overweight. The first squaw, whose son weighed 150 pounds, always placed her son on a bear hide near a pine grove; the second squaw, whose son also weighed 150 pounds, put her son on a moose hide in the shade of a large oak tree; but the third squaw, who was expecting the birth of her first son, always rested on a hippopotamus hide beside a bubbling brook. Her weight? 300 pounds! To this day, mathematicians give credit to these women and their children for proving the Pythagorean Theorem, because you see: The squaw of the hippopotamus is equal to the sons of the squaws of the other two hides."
Thank goodness Pythagorus isn't alive to see this sacrilege.
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  #25  
Old 28-05-2010, 10:23 PM
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Originally Posted by renormalised View Post
The hypotenuse is the side of the triangle which is the longest...e.g. think of a right angled triangle...the two lines which are at right angles to one another, are the adjacent and opposite lines. The line running between to two ends of those lines is the hypotenuse.
Thanks mate.

Doing wiki searches now for "Laymen" terms.
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  #26  
Old 28-05-2010, 10:50 PM
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Originally Posted by mithrandir View Post
...
The squaw of the hippopotamus is equal to the sons of the squaws of the other two hides."
Nice rendition of the tale.

Excuse the digression but it reminds me of another story ...
Preliminary-
Pythagoras' theorem states that for a right triangle with sides a, b, c (the hypotenuse), then a^2+b^2=c^2. A Pythagorean triad is a set of 3 sides for a right triangle e.g. 3,4,5 where 3^2+4^2=5^2 or 9+16=25.

In those days, Liethagoras, who was jealous of Pythagoras' fame, noticed an interesting connection between Pythagorean triads and proposed a much simpler theorem for right-angled triangles: a^2=b+c.
3,4,5 ---> 3^2=4+5
5,12,13 ---> 5^2=12+13
7,24,25 ---> 7^2=24+25

However, his fame was short-lived when it was brought to Pythagoras' attention and he laughed off the proposition.
For anyone interested, under what condition is Liethagoras correct?

Regards, Rob.
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  #27  
Old 28-05-2010, 10:54 PM
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jjjnettie (Jeanette)
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All I remember from school is the acronym
Some Old Hags Can Always Have Tea On Arrival

http://simple.wikipedia.org/wiki/Trigonometry
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  #28  
Old 28-05-2010, 11:35 PM
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Originally Posted by Barrykgerdes View Post
Digital calculators were accounted for by five on each hand and only a small fraction of the class could use these accurately in any case but we at least had trig and log tables.

Barry
Hi,

Aha yes, now did anyone use Chamber's 7 figure log tables? I still have a copy somewhere, with my Sun Hemmi slide rule.

The first calculator I ever had was a Texas Instruments SR-50 bought off a bloke who came around to my workplace (Email at Rosebery) in about 1975. He was flogging that one and a Hewlett Packard which had Reverse Polish Notation. I didn't know any forward Polish, much less RPN, so I bought the TI. I remember it cost about $350, which was an enormous amount in those days, but I claimed it on tax. I was hooked. I used to take it to meetings and calculate away, giving everyone else the pip.

Cheers
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  #29  
Old 28-05-2010, 11:37 PM
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Originally Posted by bloodhound31 View Post
Can you spell this out?

Is it saying divide 71 by whatever the value of sine is?
See page with notes and examples.
I've only done the sine ratio as a lead in to the sine rule.
Hope this helps.

Regards, Rob.
Attached Thumbnails
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  #30  
Old 29-05-2010, 12:17 AM
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Hi Barry & All,

Quote:
Originally Posted by Barrykgerdes View Post
It is a pity that so few people understand mathmatics (particularly politititans)
Oh I dunno ... politicans seem to have very highly developed counting skills.


Best,

Les D
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  #31  
Old 29-05-2010, 01:39 AM
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renormalised (Carl)
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Smile

Quote:
Originally Posted by sjastro View Post
Thank goodness Pythagorus isn't alive to see this sacrilege.
Yeah...that guy, Piethaggoris
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  #32  
Old 29-05-2010, 07:57 AM
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Originally Posted by renormalised View Post
Yeah...that guy, Piethaggoris
Known to his friends as "The Python".
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  #33  
Old 29-05-2010, 08:11 AM
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Quote:
Originally Posted by Robh View Post
Nice rendition of the tale.

Excuse the digression but it reminds me of another story ...
Preliminary-
Pythagoras' theorem states that for a right triangle with sides a, b, c (the hypotenuse), then a^2+b^2=c^2. A Pythagorean triad is a set of 3 sides for a right triangle e.g. 3,4,5 where 3^2+4^2=5^2 or 9+16=25.

In those days, Liethagoras, who was jealous of Pythagoras' fame, noticed an interesting connection between Pythagorean triads and proposed a much simpler theorem for right-angled triangles: a^2=b+c.
3,4,5 ---> 3^2=4+5
5,12,13 ---> 5^2=12+13
7,24,25 ---> 7^2=24+25

However, his fame was short-lived when it was brought to Pythagoras' attention and he laughed off the proposition.
For anyone interested, under what condition is Liethagoras correct?

Regards, Rob.
c^2=a^2+b^2
a^2=c^2-b^2
a^2=(c+b)(c-b)

Hence a^2=(b+c) if (c-b)=1.

Regards

Steven

Last edited by sjastro; 29-05-2010 at 09:20 AM.
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  #34  
Old 29-05-2010, 09:28 AM
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sheeny (Al)
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Originally Posted by GeoffW1 View Post
Hi,

Aha yes, now did anyone use Chamber's 7 figure log tables? I still have a copy somewhere, with my Sun Hemmi slide rule.

Cheers
Dunno. I should have a copy somewhere, but I haven't seen it since we moved 2 years ago.

I did, however, spot my father's hand-me-down sliderule in the drawer just the other night!

Al.
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  #35  
Old 29-05-2010, 10:24 AM
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Quote:
Originally Posted by sjastro View Post
c^2=a^2+b^2
a^2=c^2-b^2
a^2=(c+b)(c-b)

Hence a^2=(b+c) if (c-b)=1.

Regards

Steven
Great to see someone take the time out to derive the condition.
Pythagoras would be pleased!

Regards, Rob.
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  #36  
Old 29-05-2010, 10:51 AM
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renormalised (Carl)
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Quote:
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Known to his friends as "The Python".
Don't you mean "The Monty Python"??!!
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  #37  
Old 29-05-2010, 12:10 PM
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Quote:
Originally Posted by sjastro View Post
c^2=a^2+b^2
a^2=c^2-b^2
a^2=(c+b)(c-b)

Hence a^2=(b+c) if (c-b)=1.
True for all odd integers a>1.

a=2n+1
(for some n in J+)
a^2 = 2n^2+2n+1 = (n^2+n+1) + (n^2+n)

and so

c=n^2+n+1
b=n^2+n

Also true for a=1 if you allow the degenerate triangle (1,1,0).

30+ years since I finished Uni (maths, stats, comp sci)
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  #38  
Old 29-05-2010, 12:45 PM
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Quote:
Originally Posted by mithrandir View Post
True for all odd integers a>1.

a=2n+1
(for some n in J+)
a^2 = 2n^2+2n+1 = (n^2+n+1) + (n^2+n)

and so

c=n^2+n+1
b=n^2+n

Also true for a=1 if you allow the degenerate triangle (1,1,0).

30+ years since I finished Uni (maths, stats, comp sci)
Oversight in expansion ...
a^2 = (2n+1)^2 = 4n^2+4n+1 = (2n^2+2n) + (2n^2+2n+1)

Therefore can select
b = 2n^2+2n = n((2n+1)+1) = n(a+1)
c = 2n^2+2n+1 = b+1

However, the end result still works out the same.
For any odd integer a, you can always find two consecutive integers b,c to complete the triad.
e.g. a = 9
a = 2n+1 = 9 ---> n = 4
b = n(a+1) = 4(9+1) = 40
c = 40+1 = 41
Triad 9,40,41.

Interesting.
Thanks for that, Rob.
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  #39  
Old 29-05-2010, 02:36 PM
Barrykgerdes
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Originally Posted by GeoffW1 View Post
Hi,

The first calculator I ever had was a Texas Instruments SR-50 bought off a bloke who came around to my workplace (Email at Rosebery) in about 1975. He was flogging that one and a Hewlett Packard which had Reverse Polish Notation. I didn't know any forward Polish, much less RPN, so I bought the TI. I remember it cost about $350, which was an enormous amount in those days, but I claimed it on tax. I was hooked. I used to take it to meetings and calculate away, giving everyone else the pip.

Cheers
My first calculator was bought for 29 pounds in 1963 when I was earning 21 pounds a week (for those who understand not LSD, $58 and $42 respectively). It did square roots with a key press. Its greatest problem was it ran from a peculiar battery that I could never find a replacement for so I could eventually only use it from a PS that I built.

My next calculator was a HP45? bought under student discount for about $250, I think, in 1970. It was great. I loved the RPN and even more the direct polar/cartesian conversion. This was handy as I was doing a measurement on a 36' whip aerial with an RF bridge and a B40 receiver and doing dozens of calcs by hand to plot a Smith Chart. Saved me about a week. I loaned the calculator to my son in 1978 and have not seen it since.

For those who never used RPN it was like entering the steps of a calculation in the reverse order then pressing the "Go" button to get an answer. way to Go!

Barry
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  #40  
Old 29-05-2010, 03:03 PM
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multiweb (Marc)
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Quote:
Originally Posted by sheeny View Post
sin is the standard abbreviation for sine which is the ratio of the opposite side of a right triangle divided by the hypotenuse.
Actually it's much simpler than that. Sine used to be the name of this greek guy who liked his vino too much and used to walk around in the weirdest of patterns. The name stuck and the rest is history. ... so says his mate "co".
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