The correct formula for finding geometric probability using area is:
P(E) = Area of Favorable Outcomes / Total Area
This formula expresses the probability of an event (E) in terms of the ratio of the area of favorable outcomes to the total area in a given space.
The other options you provided (A = πr² and A = length x width) are formulas for calculating the area of a circle and a rectangle, respectively, but they are not relevant to the concept of geometric probability itself.