This is probably a very obvious question, but I am going through the problems listed here: http://users.cms.caltech.edu/~vidick/teaching/120_qcrypto/HW1_solutions.pdf

and, I don't understand in 1b) why it says that its obvious that <orth(Psi_1)|Psi_2>| would equal sin(theta) given that |<Psi_1|Psi_2>| = cos(theta)