how do I calculate the minimum or maximum value of the missing side of a triangle with the other sides measuring 7cm and 15. cm ?
Use the cosine rule:
c²=a²+b²-2ab cos(C)
with a=7, b=15, and included angle C would vary from 0 to 180 degrees.
Note that these limits themselves are not valid values, i.e.
max>c>min.
They represent the sum and difference of the two sides.