Question

why lines of latitude are not of equal length​

Answer 1

because of the centrifugal force of earth which make it bulge at equator and compress the north and south part

Answer 2

Answer:

We all know that the lines in the latitude are not of equal length and only the lines of longitude are of equal length.

There is a very important reason behind this phenomenon.

To tell you the truth, the centrifugal force of Earth that makes it bulge (and take up the shape that we see) at equator and compress the north and south part.