What was the name of the treatise in which euclid compiled all the existing geometric knowledge, along with some of his own observations, to provide a logical structure and progression for geometry?

The coverage of a base station of a telecommunication company forms a disk with a radius of (kilometers). let be the distance of a cellphone from a base station. assume that the location of cellphones in use are randomly uniformly distributed within the disk. calculate the mean and variance for the random variable.