How to write a program in matlab?

Question

Informatics

I have no idea how to do it, I need at least one sample. I only know that switch, case, otherwise commands are used. Who is not difficult, help, please, I will be very grateful.
The elements of an equilateral triangle are numbered as follows: 1 -
side (a), 2 - radius of the inscribed circle (R1), 3 - radius of the circumscribed circle
(R2), 4 - area (S). The number of one of these elements and its value are given. Output
the values ​​of the remaining elements of the given triangle (in the same order).