Question

tell me something about inner core

Answer 1

the inner core of any triangle rectangle or any other thing is the cone which is developed internally

Answer 2

The inner core is the very center of the Earth, and the hottest part of the planet. It is a mainly a solid ball with a radius of about 1,220 km (760 mi), according to seismological studies.[1][2] It is believed to consist mostly of an iron–nickel alloy and to be about the same temperature as the surface of the Sun: about 5700 K (5400 °C).[3]

The inner core was discovered by Inge Lehmann in 1929, using seismology. 

The inner core is more than 5,000 kilometers below the earth's surface. The pressure in Earth's inner core is about 3,500,000 atmospheres.[4] Iron can only be solid at such high temperatures because its melting temperature increases dramatically at such pressures.