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math fromula Answered

thought this would be an appropriate place to share some of what i thought was interesting information to do with the area of a triangle and how numbers co-relate.

To round off a square to 100cm square, one quarter of that area is 25cm square, (10cmx10cm =100/(div)25%=25cm), the area of a  right angle triangle with sides measuring ~7.0710cm,  equals ~25% of 100cm square,  25cm square of area,  (7.0710/2=3.5355 x7.0710=24.9995205).

7.5937 if it is an equilateral triangle.

it is a standard size i use,  a handy measurement if you use templates for construction because it in  some way represents a metric increment,

thanks,

Kim

(the formula i used is half the base times the height,  unless im mistaken i recall that is the correct formula?  though i am not a full time mathamatician.  for the equalateral triangle i used a web based polygon area calculator.)

8 Replies

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lemonie (author)2012-08-29

There was a Greek Guy called Pythagoras who figured-out triangles about 2500 years ago.

L

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Goodhart (author)lemonie2012-08-29

And IIRC, someone did so even earlier....although few records of it exist.

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kelseymh (author)Goodhart2012-08-29

Egyptian engineers certainly used the "3-4-5" relationship to make carpenter's squares. The Babylonians also knew (the "Plimpton 322" tablet) of the general relationship.

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QSDR (author)kelseymh2012-08-31

i saw a doco on egyptian building they showed a variation of a water level,
The device is calibrated by the base point(s) located on the surface of water and the position of the string is marked, (probably with a scribe back in the day). perhaps a stonemasons level.

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Goodhart (author)kelseymh2012-08-30

I thought I remembered something along those lines from high school courses many decades ago (about 4 actually) ;-)

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kelseymh (author)2012-08-29

All you've done is to cut your square along the diagonals. Each of the resulting quarters is obviously a right triangle, with hypotenuse equal to the side of the square, and sides both equal to 1/sqrt(2) times the hypotenuse.

It's a pity you just copied the output of some Web-based calculator, rather than learning the underlying geometrical relationships involved.

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lemonie (author)kelseymh2012-08-30

It's a pity you just copied the output of some Web-based calculator, rather than learning the underlying geometrical relationships involved.

You're so spiteful sometimes... that made me laugh, I'm still smiling.

L

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steveastrouk (author)2012-08-29

AKA the 1:1:root(2) triangle.

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