Coordinates of point inside of circle I'm sorry if what I'm asking has already been answered or is really easy but I struggled a little and haven't been able to come up with an idea.
TThe context is as follows: a robot is being placed inside a circle. I need to find the position the robot is being placed given that I know the center and the radius of the circle and that I have a distance sensor which gives me the distance to a point on the circle circumference. 
I believe there isn't enough information to calculate this point. If that is indeed the case could you please point me to the kind of information i'm missing?. 
Thank you in advance.
 A: Well it depends what the problem means, it is a little vague as it is stated.
Does you distance sensor gives you the distance to a fixed point on the circle? Or can you use it multiple times to get the distance to more points on the circle?
Note that if  you can use the sensor twice, for two fixed points on the circle, then you can most of the time determine the point (what I mean by most of the time is that if the two points are diametrally opposed you can only reduce the problem to two possibilities, while if the two points are closed you can find the robot)... Three points always determine the possition, no matter which three points are....
A: In this question, you are basically trying to set up a co-ordinate system.
For this, you need two things: 1. Origin 2.A fixed line (to function as your X Axis).
While you do have the origin, you need to set a line as your fixed axis.
Once you have set up the fixed line, you could use trigonometry (polar co ordinates) to find the position of the required point.
