MathDB
IMC 2011 Day 1 Problem 2

Source:

July 30, 2011
linear algebramatrixalgebrapolynomialfunctionlinear algebra unsolved

Problem Statement

Does there exist a real 3×33\times 3 matrix AA such that tr(A)=0\text{tr}(A)=0 and A2+At=I?A^2+A^t=I? (tr(A)\text{tr}(A) denotes the trace of A, AtA,\ A^t the transpose of A,A, and II is the identity matrix.)
Proposed by Moubinool Omarjee, Paris