Monday, May 19, 2014
Angle Between 2 Vectors
Binomial theroem
Friday, May 16, 2014
Rotation of conics
Determinants of Matrices
Dot product
Parametric equations
Friday, May 2, 2014
Tangnt lines
Tuesday, April 29, 2014
Random trivia
If you sneeze too hard, you can fracture a rib. If you try to suppress a sneeze, you can rupture a blood vessel in your head or neck and die. If you keep your eyes open by force, they can pop out. (DON'T TRY IT)
Every three seconds a baby is born somewhere in the world.
On average, 12 newborns will be given to the wrong parents every day.
Most lipstick contains fish scales
The most common name in the world is Mohammed.
When you die your hair still grows for a couple of months.
The most money ever paid for a cow in an auction was $1.3 million.
The sound of E.T. walking was made by someone squishing her hands in jelly.
There are 10 human body parts that are only 3 letters long (eye hip arm leg ear toe jaw rib lip gum).
A skunk's smell can be detected by a human a mile away.
The human heart creates enough pressure to squirt blood 30 feet (9 m).
When snakes are born with two heads, they fight each other for food.
The average person makes about 1,140 telephone calls each year.
Stressed is Desserts spelled backwards.
If you had enough water to fill one million goldfish bowls, you could fill an entire stadium.
Charlie Brown's father was a barber.
Dentists have recommended that a toothbrush be kept at least 6 feet (2 m) away from a toilet to avoid airborne particles resulting from the flush.
You burn more calories sleeping than you do watching TV.
A lion's roar can be heard from five miles away.
The average person spends about 2 years on the phone in a lifetime.
The largest number of children born to one woman is recorded at 69. From 1725-1765, a Russian peasant woman gave birth to 16 sets of twins, 7 sets of triplets, and 4 sets of quadruplets.
The roar that we hear when we place a seashell next to our ear is not the ocean, but rather the sound of blood surging through the veins in the ear. Any cup-shaped object placed over the ear produces the same effect
The United States has never lost a war in which mules were used.
Children grow faster in the springtime.
On average, there are 178 sesame seeds on each McDonalds BigMac bun.
7.5 million toothpicks can be created from a cord of wood.
The plastic things on the end of shoelaces are called aglets.
About 200,000,000 M&Ms are sold each day in the United States.
There are no clocks in Las Vegas gambling casinos.
The numbers "172" can be found on the back of the US 5 dollar bill, in the bushes at the base of the Linc
Women blink nearly twice as much as men.
Every year approximately 2,500 left-handed people are killed by using object or machinery designed for right-handed people.
Turtles can breathe through their butts
It’s estimated that at any one time around 0.7% of the world’s population is drunk.
More people are kill by falling coconuts every year then sharks attack
Mel Blanc (the voice of Bugs Bunny) was allergic to carrots
The only 15 letter word that can be spelled without repeating a letter is uncopyrightable.
Forty percent of Americans iron their clothes while wearing their underwear or being completely naked.
If you eat enough carrots, your skin will eventually turn orange.
Porcupines float in water.
Bookkeeper is the only word in the english language that has 3 letters that consecutively repeat.
Ants do not sleep.
Between 1902 and 1907, the same tiger killed 434 people in India.
315 entries in Webster’s 1996 dictionary were misspelled.
The winter of 1932 was so cold that Niagara Falls froze completely solid.
I am. is the shortest complete sentence in the English language.
Annually Americans eat 45 million turkeys at Thanksgiving.
Los Angeles’ full name is “El Pueblo de Nuestra Senora la Reina de los Angeles de Porciuncula.”
The Ramses brand condom is named after the great pharoh Ramses II who fathered over 160 children.
There are 66 million different possible pizza combinations on the Domino's pizza menu.
Americans, on average, spend 18% of his or her income on transportation as compared to only 13% spent on food.
A giraffe can lick it's own ears.
Ketchup was sold in the 1830s as medicine.
The most overdue book in the world was borrowed from Sidney Sussex College in Cambridge, England and was returned 288 years later.
A giraffe's heart weighs an incredible 24 pounds.
Walt Disney was afraid of mice.
The word “lethologica” describes the state of not being able to remember the word you want.
The original Coca Cola was green in color.
It would take 1.2 million mosquitoes biting you simultaneously to drain all your blood.
No piece of paper can be folded in half more than 7 times.
Donkeys kill more people annually than plane crashes.
Canadians drink more coffee than anyone else in the world.
Evaluating Limits
Wednesday, April 9, 2014
Distance, midpoint, and sphere formulas
Tuesday, April 8, 2014
Cross products
Squaring numbers between 60 & 40
Here's a quick way to square numbers between 40 and 60. You know the squares of 40, 50, and 60, right?
So let's show what to do for N=51 through 59. Write N as (50+R) for R between 1 and 9. Then N2 will have first two digits (25+R) and last two digits R2. Thus:
The rule for N=41 through 49 is similar. Write N as (40+R) for R between 1 and 9. Then N2 will have first two digits (15+R) and last two digits (10-R)2. So:
Wednesday, March 26, 2014
Conic sections on a Polar Graph
Tuesday, March 25, 2014
Math is fun.
Polar coordinates
Friday, March 14, 2014
Fun facts of the day
The numerical digits we use today such as 1, 2 and 3 are based on the Hindu-Arabic numeral system developed over 1000 years ago.
Different names for the number 0 include zero, nought, naught, nil, zilch and zip.
The smallest ten prime numbers are: 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29.
2 and 5 are the only prime numbers that end with a 2 or a 5.
The golden ratio of approximately 1.618 between two quantities such as lengths often appears in nature (tree branching, uncurling ferns, pine cone arrangements etc) and has been used throughout history to create aesthetically pleasing designs and art works such as Leonardo da Vinci’s Mona Lisa.
Fibonacci numbers are named after Italian mathematician Leonardo of Pisa (better known as Fibonacci) who introduced them to Western Europe after they had earlier been described by Indian mathematicians. They are related to the golden ratio and proceed in the following order: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, .... Can you see the pattern?
The number Pi (the ratio of the circumference to the diameter of a circle) can’t be expressed as a fraction, making it an irrational number. It never repeats and never ends when written as a decimal.
Here is Pi written to 100 decimal places:
3.1415926535897932384626433832795028841971693993751
058209749445923078164062862089986280348253421170679What comes after a million, billion and trillion? A quadrillion, quintillion, sextillion, septillion, octillion, nonillion, decillion and undecillion.
The name of the popular search engine ‘Google’ came from a misspelling of the word ‘googol’, which is a very large number (the number one followed by one hundred zeros to be exact).
A ‘googolplex’ is the number 1 followed by a googol zeros, a number so ridiculously big that it can’t be written because there literally isn't enough room in the entire universe to fit it in!
Check out some more big numbers.
You might have heard the word ‘infinity’ before or seen its symbol that looks like the number 8 placed on its side. Infinity means a limitless quantity or something that goes on forever. While it’s not really a number like 1, 2 or 3, infinity is often used in math as part of equations and formulas.
12 + 3 - 4 + 5 + 67 + 8 + 9 = 100
Elipses
Parabolas
Tuesday, February 25, 2014
Math Changes your View on the World
Trying to make math cool is like trying to make "not holding your breath for five minutes" cool: It already is, and anyone thinking otherwise struggles through life with significantly reduced mental abilities. Anyone born into a world based entirely on numbers with little dollar signs in front of them, then deciding they don't need to know numbers, is volunteering to be a very small one adding up to someone else's very big one.
But accounting is to math what diapers are to biochemistry: dealing with the stinking mess left by some unfortunate and immature side effects of being alive while doing it. Mathematics isn't cool in the same way spacetime isn't real estate. It's much bigger and more important than the ridiculous little structures we've erected on it. And anyone who doesn't understand how truly cool it is (2.725 K) simply doesn't appreciate the sheer scale of it.
We found reality's programming language. Physics is the operating system, but it's written in equations. E=mc^2 defines large parts of reality in fewer bytes than it takes to say "my penis" and has similar effects on local spacetime, ladies (~ 90 percent, + gentlemen ~ 10 percent). But that's physics. There are pure mathematical equations which are just as capable of blowing your mind.
#5. Infinite Pi
Pi is the ratio of a circle's diameter to its circumference, in the same way nuclear fission is a way of powering TVs to watch America's Got Talent: an appallingly simple effect of a reality-defining truth. Pi isn't a number, it's a startup constant of spacetime. Take a line in one dimension, rotate it around another, and the resulting ratio of lengths is a precise number. The existence of space has a numerical signature. It's called a transcendental number, because even attempting to think about how much it means is more mind-expanding than all the drugs.
Calculating pi has become the computer scientist equivalent of tuning muscle cars: we don't actually need more digits for anything useful, because the basics do everything we actually need it for, but we've spent years stacking up air-cooled hardware just because. In 1985 it was calculated to 17 million digits. Srinivasa Ramanujan found the formula used. Around 1910.
It wasn't the only such formula, but was incredibly useful because it converged exponentially compared to other algorithms, making it ideal for computers. Interesting note: at the time there was no such thing as computers. Srinivasa Ramanujan had pre-empted processors by decades. In 1985 his formula was used in the world record calculation of pi to 17 million digits, and a slight variant modified by David and Gregory Chudnovsky now holds the title at 10 trillion. We're not saying he's a robot, but if a perfect calculating machine ever goes missing in a time travel experiment we already know where it ended up.
#4. Dividing By Zero
Dividing by zero gives you undefined, infinity, or who cares, depending on whether you're talking to a mathematician, physicist, or engineer. You can tell a lot about how disconnected someone is from reality by how they contemplate infinity. For example, cult leaders often explain how infinity after nothingness means you should obey them.
At its most basic, division means, "How many times can you take this out of that?" For example, you can take a human head from the members of One Direction five times before you get blessed silence. On the one hand you can take nothing out of something an infinite number of times, but on the other, no, you can't, because that would take forever. It's a mathematical problem so hard it once crippled a U.S. Navy cruiser. The USS Yorktown's experimental military computer control system tried it and was crippled by a buffer overrun. Making this the first ship to overflow without any water. On the upside, it's way easier than asking a computer to define love or telling it that truth is a lie, or asking if those are both the same question.
The solution is as brilliant as it sounds stupid. You deal with the impossible by sneaking up on it. It's nice to know calculus solves problems the same way SEAL teams do it: sneakily and permanently.
Taking the limit as X goes to zero means that you never actually get there, but you get as close as you need to be, no matter how close that is. Then the "limit" as you tend toward zero -- but never actually reach it -- gives you the answer. As X gets small, sin X is approximately equal to X, so you're always dividing something by itself and getting one. Then, with a particularly cunning flourish, you end up dividing nothingness by itself and becoming one. Which I think means mathematics is the king of zen.
There's a fairly easy proof using the squeeze theorem. Which doubles as a good line when you want to chat up a mathematician.
These limits as you hit zero, which is a much less depressing sentence in mathematics, are essential for calculus. And calculus is essential for everything. If math is the programming language of reality, calculus is the graphics processor working out things like explosions, lasers, and gravity, all the cool special effects. Or as we call them in physics, effects.
#3. Pick A Digit, Any Digit (of Pi)
If the Ramanujan formula was transcendent understanding of reality by the human brain, the Bailey-Borwein-Plouffe formula is outright sorcery. Developed by Simon Plouffe in 1995, this formula lets you skip straight to any digit of pi without working out the rest of the number.
You want the the 10-trillion-and-33rd digit of pi? No problem. There's a fundamental constant of reality and now, without any input apart from being in the same reality, this equation can read out any part of it. That's like pulling rabbits out of a hat where the rabbits are Star Trek energy beings and your hat is a beret.
The process of using the formula sounds like someone found a glitch in god's computer. If you want the Nth term, you split the infinite sum at the Nth term, and a bit of modulo math skims out the required digit in hexadecimal. That sounds like something you'd read on Mr Mxyzptlk's GameFAQ. Reality, mathematics, and the design of 8-bit computers lining up to accidentally output one of the universe's BIOS settings. The craziest part? It's still slower than Ramanujan for finding the whole thing. It really is just a cheat code for reality.
Binomial Expansion
Well ordering principle
Well-ordering principle: Every nonempty subset T of N has a least element. Thatis,thereisanm∈T suchthatm≤nforalln∈T.
Intutively clear as it may seem at the first glance, this principle turns out to be logically equivalent to the mathematical induction, the fifth axiom of Peano, which is quite surprising.
Theorem 1. The mathematical induction is logically equivalent to the well-ordering principle.
Proof. Part I. We show the well-ordering principle implies the math- ematical induction.
LetS⊂Nbesuchthat1∈Sandk∈Simpliesk′∈S. Wewant to establish that S = N by the well-ordering principle.
Suppose N\S is not empty. Then by the well-ordering principle there is a least element m ∈ N\S. Since 1 ∈ S we know 1 ∈/ N\S. Therefore m ̸= 1 and so by one of the homework 2 problems there is some q ∈ N such that m = q′ = q+1, which implies q < m by the definition of <. Weconcludethatq∈S;orelsewewouldhaveq∈N\Sandso m would not be the least element of N \ S, which is absurd. However, since S has the property that k ∈ S implies k′ ∈ S, we conclude that m = q′ ∈ S because q ∈ S. This contradicts m ∈ N \ S.
The contradiction establishes that N \ S is empty. Hence S = N. Part II. We show the mathematical induction implies the well-ordering principle.
Let S(n) be the statement: Any set of natural numbers containing a natural number ≤ n has a least element. Consider the set
E ={m∈N:S(m) is true}.
1 ∈ E because 1 is the least element of N (why?).
Wenextshowm∈Eimpliesm′∈E. Nowm∈EmeansifXis a subset of N containing a natural number ≤ m, then X has a least element. From this we want to establish m′ ∈ E.
So let C be any subset of N containing a natural number ≤ m′. If C has no element < m′, then m′ is the least element of C and we are done. Otherwise, we can now suppose there is a natural number y ∈ C such that y < m′. In particular, y ≤ m because by one of the homework 3 problems we know there is no natural number strictly between m and m′. Therefore, C now has an element y ≤ m, so that the induction hypothesis given in the preceding paragraph implies that C has a least element. In any event, we have proven C has a least element, so that
m′ ∈ E. Hence, the mathematical induction implies E = N.
In summary, the mathematical induction implies that the statement S(n) is true for all n ∈ N.
Wednesday, February 19, 2014
Amaze the Teach
Who doesn't love magic tricks? Here, we're going to look at how you can amaze your friends with some simple tricks involving numbers. You don't need a long-sleeve shirt, a rabbit, or even know the slightest bit of magic – just a little math.
Let's start off with a simple math trick.
Lightning Addition
Proclaim to your friends: “I'm a human calculator! I can add five 3-digit numbers quicker than you can punch in the numbers in a calculator.” Then ask three friends to write down three separate and random 3-digit numbers. For instance:
240
520
842
Ask them to return the paper, upon which you add in the final two 3-digit numbers.
240
526
842
759
473
Race against your friends, who are armed with a calculator, to add all these numbers up, while you blurt out the answer within a matter of seconds: 2,840.
The secret: The last two numbers you throw in isn't random at all – it may look random to your friends, but you've carefully chosen them so that the fourth and first numbers add up to 999 (in the example above, it would be 759, since 240 + 759 = 999). Choose the fifth number so that it adds with the second number to give 999 (473 + 526 = 999).
Once you have that down, the rest is simple: the sum is 2,000, add the number in the middle, and subtract 2. And voila! 2,840.
Lightning Addition 2
If your friends weren't too impressed by that trick, try this one. Ask a friend to pick two different single-digit numbers (for example, 4 and 7) and add them up (4 + 7 = 11). Tell them to do it in secret, so that you can't see what numbers they chose, or what they're doing.
Now, ask them to take the sum of the first two numbers (11), and add it to the number prior to that (which is 7). So the chain of calculations now appears to be as such:
4
+7
+11
18
Continue on the chain of addition until he reaches 10 numbers.
4
+7
+11
+18
+29
+47
+76
+123
+199
+322
????
Once done, ask your friend to show you the chain of numbers. Here comes the amazing part: challenge your friend, who's armed with a calculator, to figure the sum of all these 10 numbers, while you figure out the answer in less than five seconds – which is 836.
The secret: It turns out that this pattern of addition follows the Fibonacci sequence of numbers, which is the basis for the Fibonacci ratio. You might know it as the Golden Ratio, which often occurs in nature.
The trick here is that the seventh number in the sequence, multiplied by 11, will always equal the sum of the 10-number sequence. In this case, it's 76 x 11 = 836.
Wait a minute, you say. How does one multiply the number by 11 in under five seconds? Here's where you use another arithmetic trick: Take the two numbers, 7 and 6, and split it, leaving a blank space in the middle:
7 __ 6
In the space between, place the sum of the two numbers:
7 13 6
Because the space in between 7 and 6 can only have one digit, carry forward 1 to 7, and what you end up with is:
836
Simple? Try it with 48 x 11
4 __ 8
Place the sum of the two numbers
4 12 8
Then, carry forward the 1 to the 4
528
Note: If your friend starts off with 9 and 7, or 9 and 8, the seventh number would be a 3-digit number (101 and 109, respectively). In these special cases, just remember that the result after multiplying them by 11 is 1,111, and 1,199 respectively.