Problem: If the radius of a circle is a rational number, its area is given by a number which is:
Answer Choices:
A. (rational)
B. (irrational)
C. (integral)
D. (a perfect square)
E. (none of these)
Solution:
Since and is irrational and is rational, is irrational. (The product of a rational number and an irrational number is irrational.)