Let's think through this step-by-step:
We have a circle of radius 1
Two points are chosen at random on the circle
We want to find the probability that the distance between the two points is at most 1
To find the probability, we need to calculate:
The number of possibilities where the distance is at most 1
The total number of possibilities
Then divide the first by the second
To count the possibilities where the distance is at most 1:
** The two points can be anywhere on the circle, as long as they are at most 1 unit apart. This forms a "slice" of the circle with an central angle of up to pi radians (since the circle has circumference 2pi and radius 1).
** The area of a slice of a circle is (pi * r^2) * (theta / 360) where r is the radius and theta is the measure of the central angle in degrees. Here, r = 1 and theta = 180 degrees (since pi radians = 180 degrees), so the area of the slice is (pi * 1^2) * (180/360) = pi/2 square units.
** Since the points can be anywhere in this slice, the number of possibilities is (area of slice) = pi/2
The total number of possibilities is the area of the entire circle = pi.
Therefore, the probability is (pi/2) / pi = 1/2