Vastu has many rules for the shape of a plot. Some rules were made regarding the establishment of Vastu Purusha in a square plot. These rules have given rise to many illusions among the people which make it difficult to understand its real form. A proper implementation of these rules bring auspicious results otherwise enhances problems.
If any angle of a corner is increased then it proves that at least two arms of the plot are more than the fixed ratio. In this case the land is not either rectangular or square. If these extended arms meet at a point then their angle is less than 90o. In this case the result of the land changes.
Any extension in Ishaan which is on the northen boundary also extends the northen direction and the Ishaan direction. The extension of these direction is considered auspicious, because it gives more activition to the Vastu Purush, Vastu Purush is lying with his head embedded in the land. Hence, in Ishaan lies the back side of his head. Medical sciences also states importance of the back side of the head. Hence this extension is very auspicious.
Extension on the eastern boundary extended towards the eastern direction which also extends the Ishaan is comparatively less auspicious. Extension in east creates problems related to child and neighbours. This region is the southern part of the head and the hand of the Vastu Purusha. Their activation brings profits for the owner but at the same time could create problems like diseases, loss of money, disputes, a legal complication etc. In long terms it makes a factory to be sold.
An extension in Vayavya technically increases the Nairatya and the West direction which is considered inauspicious. Those extensions invite raids of income tax, provident funds, etc it could make a person bankrupt, transfer of one’s good luck to his enemy.
Extension of Nairaitya brings accidents, legal disputes, inability of the sons and losses. It could completely end a financial instatuts. This extension is most disastrous as it allows the entry of evil tendency. Extensions of south and nairaitya give birth to diseases, court cases etc. This ultimately tead to complete destruction.
An extension in Agni corner increases the element agni. Its efect can be seen in the temprament of the owner of land. It could lead to division of property after disputes. This is applicable to even big indurtual houses. This extension effects east and agni corner together. It also proves to be a cut in the Ishaan. This situation gives rise to ill fate, wrong decisions, economic loss due to competition, insult etc. The opposition and disputes between the sons and the owner, disintegrate the family.
Any extension in cardinal direction is also not considered good. It comes in the category of fragmented corners. Extension of only one corner is considered auspicious i.e. the Ishaan Corner.