i've been given a problem to find the eigenvalues of R = RyRz given theta = pi/2. Ry and Rz are your standard rotation matrixes, so

the real one is simple enough, but when i try to sub in lander i get

(0-lander)0 1

1 (0-lander)0

0 1 (0-lander)

which is evaluating as -

(0 - lander)^3 + 1 = 0

so the real solution is 1, as it should be for a rotation. but i cant see where the complex solution could be. should i have kept the equation as trig functions maybe ?

thanks