Why isn't there समास in this book.

We are having समास in the exam.

So Experts, in दविगु समास , For example if it is given

To find the compound of त्रिभुज,

Then i write तीन भुजाओं का समूह

If it is asked to find the compound of त्रिकाल, then i write-
तीन कालों का समाहार

Now the question is, the last word of the answer is either  समाहार or समूह in दविगु समास , i dont know what to write, समाहार or समूह, is there a certain pattern for it. then please tell me.

i hope you have understood my doubt.

What does writing समाहार or समूह  depend on?

So, in other words i dont know what to write in the end in दविगु समास. समाहार or समूह?

Please explain Experts.