How to find if an aircraft is inside an airspace using latitude and longitude? I have the data of latitude and longitude of $n$ points on the boundary of the airspace of a country. I also have the coordinates of the current location of an aircraft. Using this data, how do I find out of the aircraft is inside the airspace or outside.

For the sake of simplicity we can assume the boundaries of the airspace form a convex polygon.
It is just a well-known computational geometry problem called PIP (point-in-polygon). I assume that the airspace is pretty small, and we can consider its boundaries as lines (not curves) in a plane.

Firstly convert latitude and longitude minutes and seconds to fractions. Then use any of PIP algorithms (or libraries, if you do it in any programming language).

For more information check: wiki or this link.

You can also use WolframAlpha for that, or any programming language with a specific library (for example, OpenCV does it very well in C++ or python).