It has only 2 steps. This corresponds to the basic case. Something is true for the first case base case.
This corresponds to the basic case.
Assuming n 1 coso isino 1 cos. When n 0 the formula gives us 1 - 12 2 n2 1 - 122 14 a 0. It is the leverage of going from the smaller cases to the bigger one that matters. We first establish that the proposition P n is true for the lowest possible value of the positive integer n.