Peninsular plateau is triangular in shape.

Explanation:
The Peninsular plateau is a large landmass located in the southern part of India. It is formed by the Deccan Plateau, which is triangular in shape.

1. Geographical Location:
- The Peninsular plateau is bounded by the Western Ghats in the west, the Eastern Ghats in the east, and the Satpura and Vindhya mountain ranges in the north.
- It extends from the Narmada River in the north to the Kanyakumari in the south.

2. Shape of the Plateau:
- The Peninsular plateau is triangular in shape, with its apex towards the south.
- The Western Ghats form the western boundary of the plateau, running parallel to the Arabian Sea.
- The Eastern Ghats form the eastern boundary of the plateau, running parallel to the Bay of Bengal.
- The Satpura and Vindhya mountain ranges form the northern boundaries of the plateau.

3. Formation:
- The Peninsular plateau was formed due to volcanic activity and tectonic movements.
- It is composed of igneous and metamorphic rocks, which are the result of volcanic eruptions and subsequent cooling and solidification.
- The lava flows from these volcanic eruptions created the flat-topped plateaus and the rugged hills and valleys in the region.

4. Characteristics:
- The Peninsular plateau is characterized by its elevation and relief features.
- It has an average elevation of about 600-900 meters, with some parts rising to more than 1,500 meters.
- The plateau is dissected by numerous rivers, which have formed deep valleys and gorges over millions of years.
- It is rich in mineral resources such as coal, iron ore, limestone, and bauxite.

In conclusion, the Peninsular plateau is triangular in shape, with its apex towards the south. It is bounded by the Western Ghats in the west, the Eastern Ghats in the east, and the Satpura and Vindhya mountain ranges in the north. The plateau was formed due to volcanic activity and tectonic movements, and it is characterized by its elevation and relief features.