ABCD's are driving you crazy
Algebra
Level
2
\[ \begin{eqnarray} a^2 + b^2 & = & 2 \\ c^2+d^2 &=& 1 \\ (ad-bc)^2 + (ac+bd)^2 &=& \ ? \end{eqnarray} \]
by
Lakshya Singh