ABDC is a parallelogram in which diagonals AD and BC intersect at O. AE and DF are perpendicular on BC at E and F, respectively. Which of the following is not true?
ΔADC ≅ ΔABD

As we know,
In quadrilateral opposite sides are parallel and equal and its diagonals bisect each other.
Go through the option (1)
In ΔADC and In ΔABD
⇒ AC = DB(Opposite sides)
⇒ AD = AD(Common)
⇒ ∠ACD = ∠ABD (Opposite angles)
Now, we can say ΔACD ≅ ΔDBA not ΔADC ≅ ΔABD
ABCD is an isoceles trapezium such that AD||BC, AB = 5 cm, AD = 8 cm and BC = 14 cm. What is the area (in cm 2) of trapezium?
In a trapezium ABCD, DC ∥ AB, AB = 12 cm and DC = 7.2cm. What is the length of the line segment joining the mid-points of its diagonals?
In the given figure, a circle touches quadrilateral ABCD. If AB = 2x + 3, BC = 3x – 1, CD = x + 6 and DA = x + 4, then what is the value of x?

PQRS is a cyclic quadrilateral and PQ is the diameter of the circle. If ∠RPQ = 38°, then what is the value (in degrees) of ∠PSR?
PQRS is a parallelogram and its area is 300 cm 2. Side PQ is extended to X such that PQ = QX. If XS intersects QR at Y, then what is the area (in cm 2) of triangle SYR?
ABCD is a cyclic quadrilateral whose diagonals intersect at P. If AB = BC, ∠DBC = 70° and ∠BAC = 30°, then the measure of ∠PCD is:
The sides BA and DE of a regular pentagon are produced to meet at F. What is a measure of ∠EFA?
ABCD is a cyclic quadrilateral. Diagonals BD and AC intersect each other at E. If ∠BEC = 128° and ∠ECD = 25°, then what is the measure of ∠BAC?
In E is a point inside the quadrilateral ABCD where DE and CE is the angle bisector of ∠D and ∠C respectively. If ∠B is 82° and ∠DEC is 80°, then find the ∠A.
In the given figure, ABCD is a rectangle and P is a point on DC such that BC = 24 cm, DP = 10 cm, and CD = 15 cm. If AP produced intersects BC produced at Q, then find the length of AQ.

ABCD is a quadrilateral such that $\angle A = 47^\circ$, $\angle B = 66^\circ$, $\angle C = 133^\circ$ and $\angle D = 114^\circ$. What type of a quadrilateral is ABCD?