Task: Text Categorization
Input (English): This entity is the subject of the BPP algorithm. Archimedes approximated it by inscribing and circumscribing progressively larger n-gons. The probability that two integers are relatively prime is equal to six divided by the square of this. This is the definite integral from negative one to one of one over square root one minus x square dx. Lambert showed that it is (*) irrational. This is the equal to the inverse cosine of negative one. For 10 points, name this constant multiplied by the square of the radius to find the area of a circle.
Output (English): Science