If the earth is not a perfect sphere, are you able to use a compass to find latitude or angel elevation???

Answer 1

First, the earth is a more perfect sphere than any billiard ball.
Second, imperfections in the sphere have no material effect on how compasses work.

A compass shows the direction to the magnetic north pole (which is not the same as the true north pole). You can't use it to determine latitude or longitude, at least not without moving around a lot.

Answer 2

you don't use a compass, you use a secstant and you use the angle of position to the stars to determine latitude.

You also can use it to find longitude if you have the appropriate tables.