In quadrilateral PQRS$\angle P : \angle Q : \angle R : \angle S=3 :4 :6 :7$ calculate each angles of the quadrilateral and prove PQ and SR are parallels to each other:

Is PS also parallel to QR?

In quadrilateral PQRS $\angle P : \angle Q : \angle R : \angle S=3 :4 :6 :7$ calculate each angles of the quadrilateral and prove PQ and SR are parallels to each other:

Assign a special name to quadrilateral PQRS.

Use the information given in the following figure to find the value of x.

The following figure shows quadrilateral in which sides AB and DC are parallel it,$\angle A:\angle D=4:5,\angle B=(3x-15{)}^{o}and\angle C(4x+2)$ find each angle of quadrilateral.

Use the following figure to find the value of x.

ABCDE is regular pentagon the bisector of angle A of the pentagon meets the side CD in point M show that $\angle AMC={90}^0$

In a quadrilateral ABCD, AO and BO are dissectors of angle A angel B respectively, show that $\angle AOB==\frac{1}{2} (\angle C+\angle D)$