ABCD is a rectangle AC is diagonal. Find the nature of `DeltaACD`. Give reasons.

ABCD is a rectangle in which diagonal AC bisects /_A as well as /_C . Show that: ABCD is a square.

In the figure, ABCD is a quadrilateral. AC is the diagonal and DE || AC and also DE meets BC produced at E. Show that ar(ABCD) = ar (DeltaABE).

In the given figure, ABCD is a rectangle, Find the values of x and y.

In parallelogram ABCD, diagonals AC and BD are equal. Find the measure of angle ABC and prove that the quadrilateral ABCD is a rectangle.

ABCD is parallelogram and ABEF is a rectangle and DG is perpendicular on AB. Prove that (i) ar (ABCD) = ar(ABEF) (ii) ar (ABCD) = AB xx DG

A polygon has 65 diagonals, then find the number of its side.

ABCD is a parallelogram. AC and BD are the diagonals intersect at O. P and Q are the points of tri section of the diagonal BD. Prove that CQ" ||" AP and also AC bisects PQ (see figure).

ABCD is a trapezium in which AB||DC and its diagonals intersects each other at the point O. Show that (AO)/(BO)=(CO)/(DO) .

In a polygon the number of diagonals 77. Find the number of sides of the polygon.

ABCD is a parallelogram. The diagonals AC and BD intersect each other at ‘O’. Prove that ar(DeltaAOD) = ar(DeltaBOC) . (Hint: Congruent figures have equal area)