5.3.2.22 Various problems in the space

condition: B rectangle \( A B C D \quad A B: A D=2: 3 \). Through the side \( B C \) a plane \( B C E \) is drawn, with which the diagonal of the rectangle forms an angle equal to \( \alpha \). Find the angle between the planes \( B C E \) and \( A B C \) in cases where \( \alpha \) takes the value \( 30^{\circ} \).