I don't want to be that type of guy, but we shouldn't exchange code. I've done this exercise a little bit more complicated that it needed to be: I also made possible for the user to use Heron's formula (the one that calculates the area of a triangle based on the measure of the 3 sides). But yes, the split method is kind of necessary if you want to reduce the number of inputs you want to have.
More informations about .split():
its sintax is: my_string.split(separator, limit)
And It returns a list of separated strings.
if you omit the separator, its base value is " ". In general, separator is the recurring value thanks to which you want to separate the elements of the list.
limit is the maximum amount of elements in the list that we want to split:
For Example for my_string = "bas/44/33/print(ln(x))/19/10/2021", mylist.split("/", 4) will return:
['bas', '44', '33', 'print(ln(x))', '19/10/2021']
because it doesn't touch whatever else is after the value of limit