Any maths teachers on this forum?
Posted by: mista h on 29 April 2014
If you'd have been studying mechanical engineering, your lecturer wouldn't have been very happy if you used pi r squared. He certainly would have cared.
This is news to me. I can't understand why one form would be preferred over another. Assuming you have the diameter to start with and want to calculate the area. Either divide by two, square and multiply by Pi, Or square, multiply by Pi and divide by 4. Same number of steps, same outcome.
With respect to which is "preferred" I'd actually argue that dividing by 4 is slightly more difficult than dividing by 2 for most people. You also have to square a bigger number, which is perhaps more difficult. These differences are VERY subtle but are both in favour of converting to radius first. If you start with a radius then it is a no-brainer - you wouldn't convert to diameter just for the pleasure of having divide your answer by 4.
In any case, it is so absolutely trivial that I can't imagine a lecturer caring one way or the other.
I think you're either making this issue up or are confusing this with the obscure debate about whether to use Pi or Tau.
http://tauday.com/tau-manifesto
The Pi Vs Tau argument at least makes sense at some level.
I agree, it's not simpler to use d as opposed to r when calculating the area of a circle, just as niether has an advantage when calculating the second moment of inertia of a shaft, I = pi r to the power 4 over 4, v I = pi d to the power 4 over 64. etc.
It's nothing to do with the ease of use, it's simply a convention. You measure diameters, you dimension diameters, you manufacture diameters and you calculate using diameters. Introducing r into the the mix would increase the chance of an error.
Never heard of Tau, but the Pi Vs Tau argument seems pretty irrevelant to me.
To resolve this I propose a new form:
Area = Pi times (diameter/2)squared
There, I used diameter. Happy?
((can't see the point in placing brackets around numbers) (when not required)) ((as rediculous as placing brackets around words) (don't you think)) (Even if it does clarify matters) 
Does anybody know the formula for the area of a circle?
Did you ever program for a living? You have to consider the poor unfortunate coming after you and brackets and comments are always necessary. Even if you know about BODMAS (B=Brackets) it's easier to read with brackets.
I remember one of my computer science lecturers telling us that well written code needed no comments. He'd obviously never worked in a commercial environment.
If you'd have been studying mechanical engineering, your lecturer wouldn't have been very happy if you used pi r squared. He certainly would have cared.
To which my wife* responded "bollox".
*Mech Eng, Bristol Uni, 1979, C.Eng. M.I.Mech.E.
personally, I use the classic pi-r-squared.......but then, I'm just a Sparkie....what do I know? 
I think you'll find you're very much mistaken, they are - apple tree, Christmas tree, fur tree, and conker.
Looks like your counting up to five is as good as your spelling 
Once again, the placement of the missing but "implied" brackets are crucial. I get 530.
Once again, the placement of the missing but "implied" brackets are crucial. I get 530.
Trying to be too fast, I got this right, then briefly wrong. But now I agree with you on the answer. But what "implied brackets" are missing? Around the 7 and the zero? That would have prevented me from getting it momentarily wrong, so would arguably add clarity for those in a rush like me. But the expression is not ambiguous in any way provided the convention is adhered to.
My first guess, which turned out to be right was 530 on the basis that it is the only answer even close to 8 cubed, and that the only term subsequently subtracted is a 6.
Once again, the placement of the missing but "implied" brackets are crucial. I get 530.
Trying to be too fast, I got this right, then briefly wrong. But now I agree with you on the answer. But what "implied brackets" are missing? Around the 7 and the zero? That would have prevented me from getting it momentarily wrong, so would arguably add clarity for those in a rush like me. But the expression is not ambiguous in any way provided the convention is adhered to.
My first guess, which turned out to be right was 530 on the basis that it is the only answer even close to 8 cubed, and that the only term subsequently subtracted is a 6.
It's about grouping like terms together. The equation could be re-written, pedantically, as:
(8 cubed) - 6 + (3 x 8) + ((7 squared) x 0)
I.e. (512) - 6 + (24) + (0) = 530
Of course, if you're used to doing this kind of thing, then you can approximate by inspection.
Previous posters noted that BODMAS indicates you should look at "other" or "indices" after brackets. A more modern and technologically minded author might propose iBODMAS!
OK, let's quit horsing around and get down to some real math!
OK, let's quit horsing around and get down to some real math!
I have "people" to do that for me now.
I would have worked it out (honest!) only I haven't got a phi on my keyboard
OK, let's quit horsing around and get down to some real math!
I think it simply “defies” (dф) any sort of an answer…………….
OK, let's quit horsing around and get down to some real math!
I think it simply “defies” (dф) any sort of an answer…………….
Ouch.