Reply With QuoteAgreed, not as simple as it looked (to me). Ended up with polynomial 6z3+1.5z2+6z-1.5=0 where z=tan(Y) and used https://www.wolframalpha.com/input?i...2%2B6z-1.5%3D0 to solve and give same result.Originally Posted by Groundrush
I have depending on which X we are interested in. In my case it was a simple Pythagoras calculation nothing complicated.
The circumstances were working out if the height of a building was greater than 18 metres to see if the EWS1 cladding rules applied to a building. We didn’t know the height but I could use a golf laser to measure distance from the foot of the building and to the edge, then I found X ( calculated the height).
I must remember to thank my school teachers who had predicted that one day fire cladding rules would have an 18m requirement and that I couldn’t access the roof to check.
Last edited by joe narvey; 6th October 2022 at 13:24.
Agreed, not as simple as it looked (to me). Ended up with polynomial 6z3+1.5z2+6z-1.5=0 where z=tan(Y) and used https://www.wolframalpha.com/input?i...2%2B6z-1.5%3D0 to solve and give same result.
HintThis is a real world problem and one I keep coming back to, as it really annoys me!
Someone, please find X in the simplest way that they can ....
If it's a rt angle triangle then its sides are ratios of 3:4:5, then it's simple arithmetic. No need to worry about angles and sin/cos/tan...
Cheers,
Adam.
Tan y = x/6 = z
Tan 2y = (1.5+x)/6
Tan 2y = Tan y+y = (Tan y + Tan y) / (1- (Tan y)2)
(1.5 +x)/6 = (x/6 +x/6 ) / (1-(x/6)2)
1.5+x = 6*2x/6 / (1-(x2/36))
(1.5+x)(1-x2/36) = 2x
1.5 -(1.5/36)x2 + x - (1/36)x3 = 2x
(-1/36)x3 -(1.5/36)x2 - x +1.5 = 0
Which solves to 1.35452
Right enough, I oversimplified I guess.
I still think x = 3
Cheers,
Adam.
You did not oversimplify. Your affirmation is just plain wrong. In this case you have 2 unknown quantities, x and the length of the hypothenuse. You therefore need 2 equations to solve the problem.
'Against stupidity, the gods themselves struggle in vain' - Schiller.
X = 42
You Sir are a Hoopy Frood...
Drew that triangle in CAD in under a minute, got X=1.355
You must be pulling our leg
Why?You must be pulling our leg
Because you don’t seem to realise that you do algebra without realising it. Just because calling the quantity you’re looking for «*x*» doesn’t compute.
'Against stupidity, the gods themselves struggle in vain' - Schiller.
You're right, it doesn't compute. The following is a basic question on BBC Bitesize, along with the answer and calculation. Someone said earlier that (in this example) 'f' is simply the value we don't know. I've read the answer and calculation many times and there isn't any part of it that makes sense to me. None. The answer is 7f - 14 but what is f? And what's the actual question?
Let's say f (the value we don't know) is 10. 7 x 10 - 14 = 56
But we don't know the value of f so what's the point in doing the equation?
Simplify 3(f – 2) – 4(–f + 2)
Answer is: 7f – 14
Working with the first bracket we have (3 ×f) + (3 × –2) = 3f – 6.
The second bracket (be careful with signs) gives (–4 ×–f) + (–4 × 2) = 4f – 8.
Adding these two results together gives 7f– 14.
Last edited by TaketheCannoli; 6th October 2022 at 22:30.
I supplied the f value of 10 so the equation you've given, even I can work that back. My point is, what is f when I don't provide it?
Do you have children? Then tell them not to bother, maths isn't important.
What do you mean? Yes I do have children and of course maths is important. My eldest got straight As at GCSE and A Level but that doesn't mean I get algebra. I'm trying to learn it now so I can help my youngest if she needs it.
I've got a successful career and am of above average intelligence. I've also never had a maths related situation in life that I've not been able to resolve. So if you're trying to insinuate that I'm somewhat under-educated, don't.
You need as many independent equations as you have unknown quantities.
So in the example you were given with £230 and £200, you solved the problem your way but the algebraic way was to write a variant of :
x = £230-£200, where x is the amount you’ll be left with.
Your brain understands the process in everyday problems but cannot express it with algebra.
That is absolutely fine, you never wanted to do advanced maths anyway; but it needed to be taught for 2 reasons
1) because now you can do basic calculations and find a numerical value given other related figures
2) because while you did not get it, others did and went on to become engineers or rocket scientists. So you knew your future career had to be outside maths, not theirs.
'Against stupidity, the gods themselves struggle in vain' - Schiller.
Of course it's important - more so to some than others.
I am not surprised you take this view.
When you look long into an abyss, the abyss looks long into you.........
What a daft response.
You're right, thanks for understanding
And if I may: don’t worry about being able to help. She may be like you, in which case you’ll have a case of the blind leading the blind, or like her brother in which case you’ll feel (wrongly) inadequate. Instead ask her brother to help if she needs it.
As you said you worked to a successful career using the skills you had. Allow her to do the same
'Against stupidity, the gods themselves struggle in vain' - Schiller.
Fair points. I've told her she needs to seek the help of her maths teacher tomorrow.
I was being sarcastic, I have a science background myself and it's not my view.
Not surprised at you anyway.
For the record I am in exactly the opposite situation. I am more comfortable now because she’s starting to understand where her talent is, but it definitely was not in algebra, in geometry nor any thing remotely associated with maths or physics
'Against stupidity, the gods themselves struggle in vain' - Schiller.
Try to put some effort into your sarcasm.
When you look long into an abyss, the abyss looks long into you.........
Pick an argument with someone else.
Stop being such a miserable arse then.
When you look long into an abyss, the abyss looks long into you.........
Get a room you two
'Against stupidity, the gods themselves struggle in vain' - Schiller.
Okay boss.
FTFYGet a room you ((2^.5)^(2^.5))^(2^.5)
Don't just do something, sit there. - TNH
Oh, you weren't. Well others have said it better than I can, but the letter is just a symbol to represent something else. Whether the letter is x, y, z or f is irrelevant. The only reason to use multiple letters is when there's multiple unknowns.
Here have a read of this, I'm sure there's many others but it was the first on Google: https://demmelearning.com/why-we-learn-algebra/
How did they cope without a zero?
Brian has IV apples, he gives I apple to Biggus, II apples to Incontinentia and I apple to Loretta
How many apples does Brian have left?
Answer *blank*
So the kids the skip the question get a point
They could have a concept of none w/o needing a symbol for zero.
Our counting system relies on digits in columns so needs a symbol (zero) in the units, tens and other columns.
Counting with stones or on an abacus doesn't need a zero.
I have nulla
Brian
Football results innit!
What conveys more information-
Tranmere Rovers 3, Plymouth Argyle 0
or
Tranmere Rovers 3, Plymouth Argyle.
Did you get a succinct answer to your question here? I've read through to the end of the thread but not seen an actual clear answer to the (meta-)question you asked.
It seems to me that the key point of misunderstanding is that you are assuming that the goal is to find "f" but that's not the point of the question. Instead the goal is only to simplify the given expression.
And so "3(f – 2) – 4(–f + 2)" is correctly simplified to "7f - 14".
That's it.
There was never any intention to solve anything for "f".
The question is testing the student's ability to understand and simplify expressions (parts of an equation).
Indeed, you can't actually solve it as it stands because it's not an equation; it is an expression. In other words, it doesn't have an equals sign.
P.S. I should add that I think that misunderstanding the goal of the question is potentially a sign of intelligence: You were automatically over-thinking it, expecting a practical end goal rather than an academic exercise in demonstrating understanding and manipulation of a certain aspect of algebra.
Last edited by markrlondon; 7th October 2022 at 11:55.
Thanks and it's an interesting observation as it aligns to my personality in so many ways. I'm an analyst so I look for solutions. I also work hard on understanding the practical application of something. That links to me being a visual person; if I can see it, I can understand it.
Unless it's algebra :(
I still remember Some Old Hag Cracked All Her Teeth On Apples as the way to recall the basic equations of trigonometry. It had its uses as did Youngs Modulus and other equations relating to beam bending, deflection and shear forces.
My dad taught me Some People Have Curly Black Hair Through Perpetual Brushing.
This caused some confusion at the time as my school was using different terminology, although it was the above that stuck for me.
I constantly find I need to find the value of x. You’re making a film on a camera with a native resolution of 6048x4032, or 3:2. You want to shoot full frame but crop to 2.35:1. How many pixels would you crop at the top and bottom if you letterboxed it? If you put that into a 4K sequence, what would the zoom be? Then if you cropped it for a 9:16 Instagram story how wide would that be? Extremely basic stuff that wouldn’t challenge an 8 year old but it comes up all the time and you often see people go slightly blank when it happens.
Occasionally even sin / cos / tan have been useful, or Pythagoras theorem, so not being able to do basic maths would be a problem, even just for doing DIY. A basic understanding of statistics and probability can also be helpful in real life. Compound interest is definitely worth understanding, and you could see during the pandemic that many people struggled with the concept of exponential growth. I don’t think I’ve ever used anything more complex though, O-Level maths would probably cover it, but I’m glad it was taught in school.
PS - You’re not alone though OP, my mother said she was never good at maths, as she never knew what X was. Not that she couldn’t calculate the value of X in equation, more that she never understood the concept of X in the first place.
Last edited by Itsguy; 8th October 2022 at 09:49.
I think my daughter was given something about an old Hippy tripping up on Acid
'Against stupidity, the gods themselves struggle in vain' - Schiller.
OK - use by regular people; have you crossed the road lately ? Essentially you look for a car, need to estimate its distance from you and it's speed. Calculate the time it will take to travel that distance to enable you to make the walk / not walk decision.
If your maths is out it could get painful !
Sent from my moto g(7) plus using Tapatalk
Anyone else open this thread up thinking that there may be something philosophical inside?
Probably easier to understand than the maths, anyway.
Funnily enough, the problem that I put the diagram up for was a computation problem of scale, for a camera used in aerial photography when I was a photogrammetrist. We used cameras with a six-inch focal length, and this was a common computation we did. However, I always felt that there should have been an easier way of solving for X, though, as yet, I have still to find it.
As per my post of 6th October 2022, 15:36
(-1/36)x3 -(1.5/36)x2 - x +1.5 = 0
or using the values in your diagram:
(-1/62)x3 -(1.5/62)x2 - x +1.5 = 0
Use something like this to solve: https://www.calculatorsoup.com/calcu...icequation.php
You're not going to get any simpler than that.
Funnily enough my partner had a 20cm cake tin and decided she wanted to make a cake half the size. So she ordered a 10cm one from Amazon and laughed when it arrived and she realised it was of course a quarter of the size. But what size should she have ordered? Maths can be useful!
A 20cm cake, then cut it in half. Did I get it right?
Approx 14 cm will give half the area but think you’re forgetting the height which presumably should scale with the area…
No, they need to be the same height to scale correctly and be half the volume.
Reducing the height to keep the same proportions in three dimensions will lead to a slightly larger diameter (which I can’t be bothered to calculate right now).
By scale correctly I mean the height should vary as the diameter does. A tiny, very tall cake will look odd and yes the calculation will be trickier (mine was for the same height).
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