In ancient India, the shapes of altrars used for house hold rituals were:

Geometrical shapes were used to construct altars and fireplaces that housed the sacred Agni and around which many rituals such as weddings and Yagya were performed. This demonstrates that knowledge of mathematics was present in India since ancient times, and Indian mathematicians made significant contributions to the world's mathematics heritage. 

Altars and fireplaces were built to perform various rituals and to worship God. The construction of these altars and fireplaces inspired the concept of geometry. These altars were used for sacrifices, and the people followed the instructions written in sulbasutras for proper altar and fireplace positioning. In these altars, primarily two types of rituals were performed: Household rituals (worship at home)

Rituals of the community (communal worshipping)

The altars and fireplaces used for worshipping in household rituals were squares and circles. For communal rituals, the altars and fireplaces used for worshipping were geometric shapes such as rectangles, triangles, and trapeziums.