\(ABCD\) is a parallelogram in which the length of \(AB\) and \(AD\) are 2 cm and 1 cm respectively and \(\angle ABC = 60^\circ\), also the diagonals cut at \(P\) and \(\angle APB = \theta^\circ\).

Calculate the \(\textbf{exact}\) values of

i) \(AC\)

ii) \(BD\)

iii) \(\cos \theta\)