Відео

0:00 The sinner of a circle?

Hey Ben, another great video . Before I started watching your channel I could only tie a couple of simple knots. My knot skills have improved dramatically from watching your videos and following your techniques. Hope you can make more metal fabrication videos in the near future.

Excellent video Ben! Keep em coming. Someone asked me where I learned to tie knots , my response was The Texas Tradesman. You are an excellent teacher even when you say nothing at all.

This is the year 2024 you Idiot!

Did I miss it or was the laser level the way he found the center of the 60' dia silo? was this to lay out a future silo on a pad bigger than 60' giving him a place to physically put the instrument- i don't see where he could have put the instrument inside of an existing silo- or outside of an existing silo (where it would have been useless anyway.)

It works because of another theorem whereby the if an angle has its vertex on the circle the the angular measure of the arc enclosed within the rays of the angle will be twice the angular measure of the angle itself. Using a square (90 degrees) therefore encloses an arc with an angular measure or 180 degrees.

Great example of basic geometry!

How can you do the rafter on basic math

You can get all of the 30 degree lines without changing your compass radius. Once you get the first one by bisecting the 60 degree angle, you can then put the point on of the compass on the 30 degree line to get 30+60 aka 90 and then again on the 90 to get to 150. then after you get the 15 degree line, you can get do the same thing to get 75, & 135, then you only need to reset the compass once to get the remainder of the 15 degree lines.

I just run the ruler to the widest spot... run a line... then do it again in the opposing direction and viola... center

The word is indentation. There is no such word as "indention!"

GREEN PAPER....!?!?!? ARE YOU NUTS......!?!?!?

Why not just draw a rectangle or square inside the circle and draw lines from the corners? Where they cross is the center of the circle.

1. Thales's _Thales_ is not a plural word, so it takes _'s_ like every other singular noun. 2. /TAL-ess/ It's a Greek name. Initial _th_ is plosive, not soft, and the _a_ is flat, like in _flat._ The _e_ is also flat, as in _bet._ Amazing how you can rack up so many errors in just one word, but there ya go. I guess how they do teacherin' in Taxes. And you spend almost nine minutes wittering on about something that's fully explained by the diagram on the Wikipedia article. Just amazing.

Measure the outside dimension from top to bottom & split the difference. finding the center of a circle is not rocket science.

Nice demonstration. I must deploy mathematics constantly in my daily work. (Customers seem to like things built well.) :)

As an applied mathematician I sometimes slum it by watching this type of video. Machinists have all sorts of hacks they use but could never prove in any rigorous way but they do work and are based on proper Euclidean geometry. A carpenter once asked me about a rule of thumb he used fo arches and I derived it from basic ellipse properties and it made sense. 17th century mathematics was highly geometric and Newton's Principia is almost unintelligible to modern readers. Indeed, Nobel Prize winning physicist Richard Feynman once tried to replicate Newton's highly geometric proof of his inverse square law of gravitation and it defeated him because Newton relied on obscure geometric properties that we simply don't learn these days because of analytic geometry etc. Newton did a geometric derivation of the shape of minimum resistance in a fluid and althougn it was obscure he got the same answer a fluid dynamicist would get woth modern techniques. Geometry is really powerful and only involves simple tools.

Draw two segments, segment ends touching the edge of the circle, shoot a 90 degree line from center of each segment, they'll cross at center of circle

OR, if you have access to a lathe, you can chuck this material up and use a center drill in the tail stock to find the center.

All this also comes from the Lord Almighty, wonderful in counsel and magnificent in wisdom. -Isaiah 28:29

The proof you gave for Thales' theorem only concerns the very special case of an isosceles triangle. Thales' theorem is much more general.

Cool. I think this would be great to show to my geometry class. One pedantic note. I believe you are using the converse of Thales Theorem: if you have an inscribed right triangle in a circle, then the side opposite the right angle is a diameter. (In other words, Thales' theorem says "diameter implies right triangle" while you need "right triangle implies diameter.")

What brand of pencil

Amazing!

You make awesome videos dude.

Very interesting discussion of geometric principles. In your story: considering that the unfortunate structural engineer of record on this project actually thought that builders could construct the roof to within 4-mils of design elevation is both quite amusing and quite distressing at the same time! To construct it to within 1/2" of design would be impressive.

When you use a compass to draw the circle you already know where the center is.

Good stuff!

Draw any inscribed triangle in a circumference, then Trace the 3 mediatrixes. The point where they meet is the center of the circle! The prthocenter!!!

Great story and totlaly believable Different attitudes in different professions. :-)

That's pretty cool 👍

Horrible green background color Very hard to see what your doing

Watching on my phone the pencil marks on the green paper are invisible. Might be different on a computer.

Or just use the set square to box the circle and draw the diagonals; where they cross is the centre.

"Ughh, this maths is boring! When will we ever use this stuff in real life?"

Thank you for the very direct route to explaining this! The paint story is so believeable in that I heard my father talking about how his days at nuclear sites- everything was so technically right yet painfully expensive when two surfaces did not meet because of such things.

Mr. THALES from Miletus was the first Philosopher ever. I could not imagine who told him this. He was the first ever. ❤

You just be a Millwright LOL great video

At 0:56 you could have used the endpoint of one of the existing two lines, to draw the third in a right angle, of which that third is parallel to the first. The diagram becomes simpler and easier to understand.

Thale’s theorem is just the inscribed angle theorem in reverse. The right angle used is an inscribed angle, and the inscribed angle theorem states that the angle AVB is equal to half the angle AOB, where O is the origin, and A, V, and B are points that lie on the circle. So given three points on the circle and the angle 2ø between two radii, you know the inscribed angle at the third point is equal to ø. But you can also go in reverse. Given an angle of 90° inscribed in the circle, the other two points form an angle of 180° with the center, so drawing a straight line between them must intersect the center. Then you just do that twice to find the intersection of the two diameters.

Even easier then that is take any ruler and hold one edge at 1 inch and diagonally angle the other side of the ruler at some other inch mark as well on the other side of the board. The center will be half the distance of that diagonal length... Example, start the diagonal line at one inch on one side of the board and say 5 inches on the other side. The center will be at the three inch mark of the ruler...

Cheers!

The other way I have heard this is that if you start with a semi-circle and draw a line from one end to any other point on the semi-circle and then from that point to the other end of the semi-circle the angle between those lines will allways be a right angle. You are using this property in reverse by putting the vertex of a known right angle on a circle. The intersection of the right angle with the circle will be a semi-circle which lets you draw a diameter line, which by definition goes through the center of the circle. Do this a second time to prodoce a sevond diameter line and the intersection of the two diameters is the center of the circle.

Stonemasons who built cathedrals and fortresses in the Middle Ages began by establishing the unit 1 by driving two studs into the rock or into a flat stone. A firm, level floor was then built around the site. Ruler, caliper, string, chain (rigid), spirit level was all they needed. Their knowledge of how to make circles, ellipses, 90 45 degrees from a line was their magic and secret. In a few places, the studs are saved for repair work. Saw a French documentary about this, if I find it again I will link it. I apologize for the language error, this is written with google translate.

Love the story.

Bloody Yanks!! It's pronounced ''NEW-clee-er'' NOT ''NU-cu-ler''. Igroramuses....

Very useful! Now are there 2 thales theorems?

Here is another tip - how to create a right triangle when you have no rulers or levels or any equipment - only a long string and a knife. Use anything as a yardstick, and arm, a leg, a branch. Heck, stick two pegs in the ground, or use two rocks and define the distance as one unit length. Cut the string into three cords: 3, 4 and 5 units of length. Tie the ends of the cords together (3 to the 4, 4 to the 5 and 5 to the 3) and when you pull on the knots to the maximal extent, you got yourself a right triangle with the hypotenuse is the 5-units length cord. Of course, any multiple of the Pythagorean triplet would work: (6,8,10) , (9,12,15) etc. Pythagoras was a complete cultist loon, but a smart guy nonetheless.

That is not Thales theorem You are using the central angle theorem

Black pencil on green paper makes poor vision.