Question 50
One considers the rectangular parallelepiped $ABCDA'B'C'D'$ such that the measure of the dihedral angle formed by the planes ($A'BD$) and ($C'BD$) is $90^\circ$ and the measure of the dihedral angle formed by the planes ($AB'C$) and ($D'B'C$) is $60^\circ$. Determine the measure of the dihedral angle formed by the planes ($BC'D$) and ($A'C'D$).