ABCD is a trapezium with AD∥BC and AD = 4cm. If the diagonals AC and BD intersect each other at O such that AO/OC = DO/OB =1/2, then BC =
(3)
AD∥BC
and AOOC=DOOB=12
∴ ADBC=AOOC⇒4BC=12⇒BC=8 cm