studiot

At the risk of starting another silly argument, I would like to ask Does anyone have any information as to the effect of sunlight (UV) and heat on covid-19. ? How far is it degraded by these two agents? Thanks for all the information you provided. +1

Clearly they teach a different version of History in your country. If you do not know the story of De Havilland (or apparently Parsons and Turbinia and the famous experts of the that time) or the current British Government specification for emergency ventilators (as broadcast today) for covid-19 sufferers why attempt to devalue others by such comment ? Or do you think this is irrelevent to the discussion?

So ? Remember also that I was offering balance. But if you think Strange was right then What abour De Havilland? What about Charles Parsons ? What about Columbus ? Back to the present. What about the UK government published specification for ventilators ? It has direct bearing on the De Havilland question.

There's good and not so good in this but IMHO it certainly doesn't deserve a downvote. On the other hand Would you also have refused to give Noether a hearing on tha basis that she had no formal qualifications ? Now we have fair and honest balance we can say

The experts tell us that the reason why washing hands is so effective against CV is that the virus particle is held together by a fatty blob. washing with soap/detergent/surfactant attacks this blob and so the virus falls apart. Given this information I was wondering about the possibility of introducing a suitable surfactant into the lungs of seriously affected patients to reduce the concentration of virus and give their own defences a better chance. Pulmonary lavage is not common but has been done for other purposes. https://respiratory-research.biomedcentral.com/articles/10.1186/1465-9921-6-138

No I don't think they do all intersect at a common point. Normals certainly cannot. That is why I asked for proof that they were supposed to.

I am sorry if my diagram confused you. All I did was cut and paste the drawing instructions given by Dima and attempt to use them to draw a diagram. That diagram was the result. I then asked if my diagram correctly showed his intentions but was not answered.

+1 We're back to this again. It never was properly resolved.

https://www.bbc.co.uk/news/health-51906604 To be tested on volunteers in the US

No. I think perhaps there really is a language difficulty here. I don't know how they teach geometry in Russia, but 'similar' is another technical word in Mathematics that has a special meaning, This meaning relates particularly to shape. (basic) geometry distinguishes 'lines' (as straight lines) and curves which are ''line' that are not straight. An arc is part of (a segment of) a curve; a line segment is part of a line.

In Mathematics, the term 'a simplex' is used to refer to (mathematical) objects that have only one part. This is distinguished from 'a complex' that has more than one part, for example complex numbers. To enjoy the benefit of a ratio one need to be working with a set structure that allows division or fractions.

That did not answer my question. Circular arcs have only one shape, by definition of circular. You still have not clarified what this thread is all about. Please do not use the word complex in mathematical discussion, unless you are actually referring to complex numbers. Use the word complicated perhaps.

@DimaMazin I am still waiting for an answer.

You have to be careful defining an arc in that way in the case where you have a complete circle, you have one too many 'points'. In any event my post was really aimed at Dima. I was still trying to understand what he wants to do. I included you because I hoped you would chip in, you are usually so helpful. I did not want to start an argument. My simple definition of an arc is a segment of a non self-intersecting curve, as opposed to a line segment being a part of a straight line. I was not proposing to go into the niceties of Jordan and other curves. This definition of an angle as the ratio of two lengths is the reason often given as to why an angle posesses no physical units (dimensions). So angle = ArcLength/radius.

Are you referring to this? http://www.themathpage.com/aTrig/arc-length.htm#arc

So it seems that all you really want to do is present some trigonometry enabling someone to calculate an angle or its sine or cosine using a complicated forumula. You are not really defining anything at all, and should not be using that word. One very big and fundamental difference between the standard method and yours is that yours cannot be used without a coordinate system. Angles are and should be, independent of any coordinate system. This is the way conventional definitions work. That is it is a property of the standard method, using only triangles.

Like most members here I understood you wish to discuss a non approximate definition of trigonometric functions. I understood your 'arc of definition' to be an arc that somehow defines a trigonometric function. Is this the case or do you mean something else ? Schoolboys are taught exact and perfect definitions of trig functions. What is wrong with these?

Thank you for your reply. This is exactly what is puzzling myself and other members. You consistently speak of 'definition', but you are using quantities you are trying to define in your definition. (A computer would return a 'reference to undefined quantity' error) I haven't yet checked your algebra for consistently - that will take time. But you can't use something (eg the sine function) to define itself.

Here is my attempt to follow your instructions. I have used 168 degrees since this is actually divisible by 6. The arc looks like semicircle, but is actually 168o. Is joining the points as instructed supposed to create straight lines that all meet at one point? How does this help define a sine ? And more particularly the sine of what angle? It is clear you have several members interested in a technical discussion about this so it is in your own interests to engage as fully as you can.

I think Dima is referring to the description of sin and cos as 'circular trigonometric functions' and their relationship to a rotating radius vector, as opposed to hyperbolic trigonometric functions. This is also linked to the use of angles to define sides of spherical triangles. But it would be nice to have a better answer to my question since it is a lot of work to investigate each aspect in depth.

I still don't know what you want ? There are many 'definitions' of sinx and cos x. Obviously they all define the same things. So do you want me to tell you what sin and cos are? Or do you want a single formula that will calculate the value of sin or cos for any x. Remembering this value will only be 'correct' to a specific number of digits? Or do want ways of obtaining exact numeric values for any angle.? Remembering there is no single way to do this for every angle. Here are some single formulae in the form of continued products which converge at or before infinity. [math]\sin x = \left( {1 + \frac{x}{\pi }} \right)\left( {1 - \frac{x}{\pi }} \right)\left( {1 + \frac{x}{{2\pi }}} \right)\left( {1 - \frac{x}{{2\pi }}} \right)\left( {1 + \frac{x}{{3\pi }}} \right)\left( {1 - \frac{x}{{3\pi }}} \right)...[/math] [math]\cos x = \left( {1 + \frac{{2x}}{\pi }} \right)\left( {1 - \frac{{2x}}{\pi }} \right)\left( {1 + \frac{{2x}}{{3\pi }}} \right)\left( {1 - \frac{{2x}}{{3\pi }}} \right)\left( {1 + \frac{{2x}}{{5\pi }}} \right)\left( {1 - \frac{{2x}}{{5\pi }}} \right)...[/math]

Your Google translated definitions seem very oddly phrased and over complicated. Can you explain simply what you are trying to do? All trigonometric functions are already very well defined.

Substances don't 'absorb force'. It is possible to build a mechanism that sort of answers your requirement using a dome shaped piece of spring steel foil set against a ring foundation. But the foundation would have to be set against something to ultimately resist the applied force.

Try the handy answer book series, some of them are rather good and all are modern. The Handy Anatomy Answer Book The Handy Diabetes Answer Book The Handy Biology Answer Book The Handy Chemistry Answer Book etc https://www.visibleinkpress.com/s17/The-Handy-Answer-Book-Series

Indeed +1