So, I've already answered the file reading part. Check out the static function

Double.valueOf(String) for turning the text into a number. Once you have your three points, it's easily available math that you can Google. I'll help more here if needed, but, for example, for checking if it's a right triangle, you use the Pythagorean theorem on the sides and see if it's true. In this case, you'd first have to figure out your longest side for determining which side C, which is also a trivial equation.