If you point a sextant at the north star above the equator, the angle it reads out is equal to your latitude. At the equator, the angle would be 0, equal to latitude. appearing on the horizon. On flat earth, you would be looking parallel to the surface and seeing the north star on the ground at the north pole. If the north star is 3100 miles up and the distance from equator to north pole is 6250 miles, then we have a right triangle with sides of 3100 and 6250. A triangle calculator shows the angle as 25 degrees above the horizon.
How can this be?