An equilateral triangle is a triangle whose sides are equal. You
are to write a class called Triangle, using filenames triangle.h
and triangle.cpp, that will allow the creation and handling of
equilateral triangles, whose sides are integers in the range
1-39.
Details:
1. The single constructor for the Triangle class should have 3
parameters: an integer size (required), which is the length of a
side; a border character (optional, with a default of '#'); and a
fill character (optional, with...