In the figure, ABCD is a trapezium in which, AB || DC and AOOC=BOOD=12 and AB=5 cm. Find the value of CD .
10 cm
In ΔAOB and ΔCOD,
∠AOB = ∠COD
(vertically opposite angles)
AOOC=BOOD (given)
∴△AOB∼△COD
(by SAS similarity criterion)
⇒AOOC=BOOD=ABCD=12
⇒CD=2×AB=2×5=10 cm