When have you ever used...?

Ron Jones

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"Football finally came in handy…wonder when calculus will start paying off."

This statement by John Whittaker in his "BIG, BIG Dog" thread made me wonder who, outside of an education setting, has had occasion to solve a quadratic equation:eek: and why?::huh:
 
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College calculus and differential equations? Hardly ever, once every 5 years or so.

High school algebra (includes quadratic equations), geometry, trig? Fairly often, monthly.

Middle school math skills? Weekly.

Grade school cut and paste skills? Daily

J
 
Your automobile is continually doing calculus for you.:) :huh: (It was doing it long before an onboard computer had been invented.)

e^(pi*i) +1 = 0
 
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I'm working my way through all the math and algebra right now and these kind of discussions used to discourage me. I'm still going to work hard at something and do it to the best of my ability even if it's something I only use four times for the rest of my life. God gave me a wonderfully created mind, I'm gonna use it.
 
Back in my engineering days I used at best a small percentage of what was fed to me in math courses. Most of the calculus I took in college was primarily used in the physics and upper-division EE courses to prove theorems. In practice, I rarely used it. Mainly algebra, trig, and a bit of differential equations. Also some Fourier functions in certain analog signal-chain design.

Now it's basic arithmentic stuff, and a little algebra and trig. Knowing the trig identities for a right triangle is helpful in WW for determining tapers and such when all you have is a calculator on hand. Anyone remember SOHCAHTOA?

Cheers,

Kevin
 
I'll admit to having never used the quadratic in real life...

But I have used calculus once or twice. Trigonometry I still use almost daily. What always annoyed me about the way math is taught is the blanket assumption that a subject like differential equations is so advanced that it must be taught as a single subject after calculus. Years after struggling with complicated word problems in high school, I find out that they are exceedingly easy to solve as differential equations.
 
I consider myself mathematically illiterate. I wouldn't know a quadratic equation if it took me out to dinner and a movie. The last high school math class I had was geometry, and I attended that class about 5 times total. (I dropped out of high school that year, but started again the next year and finished school on the 5-year plan with straight A's my last year. I was not dumb, just resistant to authority.) Then I had a pre-engineering math class in college, and after a couple of weeks, the professor suggested I drop the course before he had to flunk me.

A few years later, I was working in the construction testing and inspection business and I used a lot of math daily. I learned that I'm pretty good at 'real world' math application, but 'book math' has never been my strong suit. I may take the long approach for solving a real world math problem, since I didn't learn some of the algebraic and geometric shortcuts, but I can usually get it figured out one way or another. I also found that for calculations that had to done more than once, I could quickly program my HP calculator (and eventually PC-based spreadsheets) to do all the hard work for me.
 
Separate the sheep from the goats

1/sin(x) = ?
1/cos(x) = ?

An electric wire hanging between 2 poles forms a curve.

What is the name of the curve?
 
Ken,

I think its a hyperbolic cosine function. One of the hyperbolic trig functions anyway.
 
Once you get past Saddle Our Horses.... I am pretty much illiterate in math, but my wife used to teach geometry and trig, though after all those years of cramming it down teenager's thick skulls, she came to feel it was pretty much useless. So every now and then I bring her a real life problem from the shop and she loves it! I remember when I told her about the 3-4-5 rule for testing square. She thought I was nuts, but quickly saw the basis for it and laughed out loud.
 
I get past everyday additions and subractions, figuring staircase angles and such, and then I'm lost to the world. I have no :huh: :dunno: clue as to some of the words you all are talking about in here.:huh:

I flunked algerbra in high school. Teacher and I did not get along. He would not help me through it like he did his pet students.
So I just sat back and flunked the whole course. [ pitched a few spit wads his way:eek: :rofl: ]
 


Now, I like that answer.:thumb: :wave:

The correct answer was given by John Downey.

The name of the curve is a Catenary. Here are two ways to state the formula, one is as John said: Y = a*cosh(x/a). The other is a function of e**x: Y = a/2 * (e**(x/a) + e**(-x/a).

cosh stands for the hyperbolic cosine of (x/a). In differential equations, the hyperbolic functions were just briefly mentioned. The Electrical Engineers get into them in depth.:doh:

Interestingly, the Gateway to the West Arch in St. Louis is an inverted catenary. The formula is given inside the arch.

OK, I didn't remember all this from 45 years ago, but I did remember that a wire between poles form a catenary, and that the formula for it was a function of e**x. Strange what you remember from a diffy-q course.

The other questions were tricky also.

1/sin x = csec x (cosecant)
1/cos x = sec x (secant)

I don't think I have used a secant function since college.:dunno:

The other day I said that your automobile does calculus before there were computers in cars. For those that were curious and those that don't give a roaring rats rear, here is the story.

The calculus machine in your car is your speedometer and odometer.
From a stop, the speedometer measures acceleration(a/sec*sec) over a period of time, and integrates that to obtain your velocity in miles/hour, or feet/sec or any other convenient measure. The odometer takes the velocity and integrates that into miles driven, or simply miles.

For those of you that think calculus is the stuff you clean off the shower tiles, the integration of a function is to add up all the infinitely small slices along a curve. Adding up the infinitely small snapshots of acceleration at infinitely short periods of time, gives you the velocity at a point of the acceleration versus time curve. Likewise, the odometer does the same operation on velocity to obtain the total distance traveled.

The sun is hurting my eyes, so I will go crawl back under my rock and be quiet.
 
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