If the sides of a quadrilateral touch a circle, prove that the sum of a pair of opposite sides is equal to the sum of the other pair.

If the sides of a quadrilateral ABCD touch a circle prove that AB+CD=BC+AD.

If the sides of a parallelogram touch a circle prove that the parallelogram is a rhombus.

A point O inside a rectangle A B C D is joined to the vertices. Prove that the sum of the areas of a pair of opposite triangles so formed is equal to the sum of the areas of other pair of triangles.

Prove that the sum of the squares of the sides of a rhombus is equal to the sum of the squares of its diagonals.

Prove that the sum of the squares of the sides of a rhombus is equal to the sum of the squares of its diagonals.

The sides of a quadrilateral are 3, 4, 5 and 6 cms. The sum of a pair of opposite angles is 120^0. Show that the area of the quadrilateral is 3sqrt(30) sq.cm.

Prove that In a parallelogram, opposite side are equal

If two sides of a cyclic quadrilateral are parallel , prove that the other two sides are equal

If the sum of squares of two sides is equal to square of third side then DeltaABC is

A quadrilateral is a parallelogram, if its one pair of opposite sides are equal and parallel.