The Brainliest Answer!
There are 90 latitudes to the north of equator and 90 latitudes to the south of the equator. Counting the equator there are 90+90+1=181 latitudes.
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It has been decided by people to keep these much imaginary latitudes. There is no reason.
what about the longitudes?
longitude lines are measured from the poles. There is a full circle of measure about them

latitude lines are measured from equator to pole. there are only 90 degrees of measure possible there.

Otherwise, there would be multiple coordinate points for the same location.

The real answer is that's just how people did it.
It is because the gobe on which all imaginary lines run has a capacity of that much only.