On Friday, 19 February 2016 at 23:56:29 UTC, Lisa wrote:
Can you please help me and explain how to create a program, which would find area of triangle and its perimeter?
First, one can't find these unless something is given. So, what is given: sides? angles? two-dimensional coordinates?
The next stop is Google for how to do that mathematically, without touching the keyboard.
Once you have the above, you may have some specific difficulty expressing that in a programming language of your choice, one which Google (again) can't resolve in a few minutes. If that is the case, please state that difficulty.