Tuesday, December 20, 2011

Finding Your Center (Of Your Pizza)

     People walk up to me all the time and ask "tell me a good math trick, something I can use in my everyday life." No, this really happens!! Well, let me tell you, I have some great ones. I know how to multiply by 9's really quickly, I can tell if a number can be divided by 3 really quickly - lots of great stuff.

     If you are like my wife, you are absolutely horrible at cutting pizza slices. I mean, you might be the worst person in the world at finding the middle of your pizza. What drives me crazy is she will cut across the pizza, clearly not hit the middle of the pizza, and then just keep going like her first cut was a good one! Can you imagine? Then, I am stuck with the task of handing out disproportionately cut pieces of pizza to people. Everyone automatically assumes that I am giving them their slice based on how I perceive their eating habits, based on their weight. That's not fair to me! I am doing that, but I wouldn't be so crass as to symbolize it through pizza sizes. Please!

     I needed to solve this problem in my household before my marriage and friendships came crashing down. I needed geometry.

     You might not be aware of a cool property that all circles have. If you pick a point on a circle, and from that point draw a right angle within the circle, the sides of that angle will intersect the circle at a diameter. Here's what I mean:
     First off, it's important to make sure we know that a diameter passes through the center of a circle. Any other line segment through a circle is called a chord:



What we want is to find the center of any random circle. (Or, really, we just want to be able to cut a bunch of diameters). Start by picking any random point (we'll call it "S" for "start." Or "square." No, wait, that's confusing. "Sircle.") Also, grab a right angle:


If I put the corner of my right angle directly on the edge of the sircle circle, the right angle will intersect the circle at two points (we'll call them A and B):


If I connect points A and B, we have a diameter:



And of course, you can repeat this process one more time to cut another diameter, and this will result in finding the center of your circle:


So, this can work for any random picture of a pizza I pull of the interwebs:

As you can see, the center that was cut in this pizza is actually slightly off. Shame.

Now we can find the center of any pizza, and avoid any awkward moments when having guests over. Ha! A great right angle to use might be the box the pizza came in, but I am sure you can find others as well.

It looks as though I have made your life a little easier by answering a question you have never asked and didn't really care about anyways. You are welcome.

(Hint: this method also works on pies, cakes, waffles and well-made pancakes, but not quiche for some weird reason).

1 comment:

Anonymous said...

I have a feeling I will now cut even more unevenly, though it will take twice as long to finally cut the first slice.