Okay so first of all I tried to make the title to sound like I understand something about mathematics, correct me if I am wrong with it.
Backstory / context:
I bumped into this problem when me and my friend were talking one night in discord about where my friend should order a pizza from. He then sent me a screenshot of the choices he had, but it was only showing two pizza places with distances to them, as each pizza place has some max delivery radius set. Suddenly a light went on in my head and I told my friend that if I he had sent me a third pizza place in the screenshot, I could find out where he lives based on the locations of the pizza places and the distances shown.
So then he sent me a picture of a third pizza place and I got to work. I have heard about triangulation before so I thought that it would be a good idea to read about how that works, but in the end I either did not understand the idea or the idea of triangulation is basically that I "kind of" know where I am, but I just don't know where that location is on the map, but since I had no idea about where this said friend lived, I came into conclusion that I don't have enough data for triangulation.
So the next thing I did was what felt like the second obvious one to me - I drew a circle around each pizza place with the distances as the circle's radiuses, probably because that is how they find people in CIA-style TV-shows. Well that did basically nothing, now I just had a VERY vague area where he might live aka. where all three circles overlap I guess.
So on I went to the third obvious thing, which was to draw a triangle through the pizza places. I then googled about finding a triangle centroid and got pretty convincing results. I figured that since the centroid point is inside all of the three circles I drew - this has to be where my friend lives. I then sent an image of my solution to my friend ready to receive applauds.
Well my solution was completely wrong. Not even close. I understand that the distances to the pizza places were probably calculated via roads and not with straight lines, so that might give me some error, but the solution of mine was too far off to blame it on error.
Unfortunately I like my and my friend's privacy, so I am not going to post an image of the original problem, but instead I spend some time in photoshop and created a fake scenario:
- Distances are not actually meters, but pixel values photoshop gave me
- Green dot is the answer, or where my fake friend lives. This point is actually unknown.
- The pizzas are locations of fake pizzerias. These are known.
- The pink lines are the distances to the pizzerias as given by the website
- The cyan and the red lines, as well as the red midpoint dots and the blue centroid dot are parts of my solution or what I have tried to do to find the green point
So how can we find the green point (where my friend lives)? Can it even be found?
In mathematical terms, like said in the title, I guess this is a question about finding an originating point for three vectors of which lengths and directions we know.
(If someone finds a use for it, I can provide the .psd file of the map image)