Square's Diagonal
Source:
February 1, 2009
geometry
Problem Statement
If the length of a diagonal of a square is a \plus{} b, then the area of the square is:
(A)\ (a \plus{} b)^2 \qquad(B)\ \frac {1}{2}(a \plus{} b)^2 \qquad(C)\ a^2 \plus{} b^2
(D)\ \frac {1}{2}(a^2 \plus{} b^2) \qquad(E)\ \text{none of these}