Trigonometry I'll never use that.

[midlife]

My first scientific calculator, a Sinclair c 1976 , used reverse polish.

Texas Ti 58, saved up foot yonks to buy one, the hige box it came in us still in the garage.

Shaun

 

[Firestorm]

I had one of those, in a wee white case that doubled as a stand. Great bit of kit.

GC

One of these

 

[jefmcg]

Sometimes knowing trig can be a distraction. I remember a fairly arrogant, but not very bright computer graphics lecturer. I'd asked him a question that was not meant to be smart, but he took it as some sort of insult. After answering, he said something very like "if you think you are so smart, try solving the problem on page xxx of my book". Yes, he was the sort of lecturer that based the course around his expensive text. The only copies he ever sold, I bet. The problem was proving that every point in a colour triangle added to 100% (or something like that) and in the book his proof was 2 pages of trigonometry. I managed to prove it before the end of the lecture in about 4 steps using similar triangles. I never shared my solution with him, because he was a vindictive little man and apparently very proud of his cumbersome solution. That question was on the exam, too, but you could pick what questions you answered and I didn't trust him to understand my answer, and I wasn't prepared to regurgitate his, so did not select that as one of my questions.

Here's the book, btw. Oh, and google tells me he's a creationist. Shock!

 

[srw]

I was trying to solve a quadratic equation while riding up a 20% climb the other day ...

I remembered that if a*x*x + b*x + c = 0 then x = (-b +or- Sqrt (b*b - 4*a*c))/(2*a).

Unfortunately, I couldn't calculate (-2.976 +or- Sqrt (2.976*2.976 - 4*11.281*37.336))/(2*11.281) in my head while grovelling uphill!

There are no real solutions. 2.whatever is about 3; 3 squared is nine; 4 * 11 * whatever is bigger than 9 so you're into the complex plane.

 

[jefmcg]

I was trying to solve a quadratic equation while riding up a 20% climb the other day ...

I remembered that if a*x*x + b*x + c = 0 then x = (-b +or- Sqrt (b*b - 4*a*c))/(2*a).

Unfortunately, I couldn't calculate (-2.976 +or- Sqrt (2.976*2.976 - 4*11.281*37.336))/(2*11.281) in my head while grovelling uphill!

Kudos!

The only maths I do on rides is to convert km to miles, so I am ready with an answer if someone asks me "how far have you ridden?" I work in km, but most people here prefer miles. I also do this on audaxes, when I am feeling tired and wondering how far it is to the next control, miles sound less. 20km? Too far! 12 miles? That's more like it.

(OK, sometimes I make up a random number and then factorise it. But that's nothing compared to solving quadratics.)

 

[srw]

May I have a drink, alcoholic, of course, after the heavy chapters involving quantum mechanics? 3.14159265358979

I once sent something very close to this as an email to my colleagues - 40-odd people with mathematical degrees and various stages towards a mathematical professional qualification. Not one of them recognised it.

 

[srw]

A pint of cold water weighs a pound and a quarter

(according to my Mum)

A pint's a pound the world around.

(According to the Yanks)

 

[jefmcg]

[QUOTE 4275225, member: 259"]How can you factorise a single number?

Unless I have misunderstood what you mean.[/QUOTE]
Prime factorisation .... turning a number into a multiplication of a set of prime numbers.

(I usually pick a number that is divisible by 8 and 9, and between 4 and 6 digits.)

 

[Tim Hall]

I have had to revisit trig lately. I am a trainer of surveyors and generally the kit does it all for you. Recently I have had to teach it at a college level and have had to show how to do it the long way.

The Cat Sat
On An Orange
And He Howled

As a 3 x 3 grid is how I remembered it. Surprisingly, considering how bad I was at maths at school, I got quite into it and even worked through a Tienstra calculation of my own.

Howled Horribly was what Tom Dowson taught us back in ninety seventy mumble. I still use it .

 

[jefmcg]

There are no real solutions. 2.whatever is about 3; 3 squared is nine; 4 * 11 * whatever is bigger than 9 so you're into the complex plane.

You've just reminded me of the joy when I first understood imaginary numbers. After years of being told there is no root of -1, they said "well, lets just call the root of -1 i" and so many nice things fell out. Then a few years later, learning the applications of this bizarre assumption to circuitry.

I need to relearn this stuff....

 

[MartinQ]

There are no real solutions. 2.whatever is about 3; 3 squared is nine; 4 * 11 * whatever is bigger than 9 so you're into the complex plane.

Thought mine was funnier (but then I always do ...)
https://www.cyclechat.net/threads/trigonometry-ill-never-use-that.200398/post-4274692

 

[jefmcg]

[QUOTE 4275238, member: 259"]Oh I see, yes I did misunderstand, thanks[/QUOTE]
It's kind of "fun". Start by making up a random number. Then change it so the last 3 digits make a multiple of 8, and the sum of all the digits is a multiple of 9. Then divide it repeatedly 2 until it's an odd number, then by 3, then by all the other primes that work. Once you have it prime factors, divide the original number by the biggest one, to make sure your sums are right.

This is one of the many ways I do long, solo, overnight rides.

 

[srw]

Thought mine was funnier (but then I always do ...)
https://www.cyclechat.net/threads/trigonometry-ill-never-use-that.200398/post-4274692

You're right - I missed it on the way through.

 

[subaqua]

Some people need to discover pubs !!

 

[ColinJ]

Kudos!

The only maths I do on rides is to convert km to miles, so I am ready with an answer if someone asks me "how far have you ridden?" I work in km, but most people here prefer miles. I also do this on audaxes, when I am feeling tired and wondering how far it is to the next control, miles sound less. 20km? Too far! 12 miles? That's more like it.

(OK, sometimes I make up a random number and then factorise it. But that's nothing compared to solving quadratics.)

Ha ha - I was joking!

When I am grovelling up 20% hills, the only thing on my mind is "How much further is it to the top of this ******* thing!"

I do do simpler calculations when out on the bike, but usually on quiet, flat country lanes!