The answer to this puzzle is two words.
The three triangular diagrams represent
the three main trigonometric functions of sine, cosine, and tangent.
It just so happens that
there is one country in the world whose first three letters match each of SIN, COS, and TAN, and those are SINGAPORE, COSTA RICA, and TANZANIA, which perfectly fit the enumerations given.
Taking the given indices, we can extract the answer: