given your triangle evaluator developed in a 09 modify a copy of it to add a log file as follows

COPY your folder “triangle” and all of its contents into a new folder “triangle_log”. Edit the contents of that folder to meet the new log file requirement. [Do not modify your A-09 files as part of this work; Leave the folder “triangle” alone.]

Create an empty text file named “mytri.log” in the folder “triangle_log”.

Change your script(s) in triangle_log so, whenever the program determines its conclusion for a set of 3 numbers entered, the program will APPEND an entry in the log file “mytri.log”.

A log entry (line) is to have this format:
the ASCII newline character (the double-quotes string “n” in PHP); then,
the three input values each followed by a semi-colons (;); then,
a short phrase summarizing the triangle conclusion (e.g. Scalene).
For example (where the n is the location of the ASCII newline char):
n3;-4;4;isoceles

The 0,0,0 that stops the script should not be entered in the log file.

No other change to the prior Triangle Evaluator is needed. Just add the Log File capability.