In the diagram below, trapezium ABCD is in horizontal plane and triangle BDE is in a vertical plane. ADB = 30°, EBD = a and DCB = 2a 2.1 2.2 2.3 Explain how you can tackle the problem. Prove that Area of ABDS Area of AABD Hence, or otherwise, prove that Area of ARDE Area of LABD = 2DE AD = 8sin²a 24 c (4) (4) (10)