How to find whether a point belongs to such a graph?

Question

Mathematics

It is necessary to write a program on the pluses to find whether a point belongs to a graph.

Answer 1

"Graph" in your terminology - a gray area? If yes, then it's just a set of ifs

if (y > 0) {
  return (y >= x) && (y*y + x*x <= 9);
} else {
  return (y >= -3) && (x <= 3) && (x >= -3) && !(y < -1 && y > -2 && x < -1 && x > -2);
}

Answer 2

Break the area into simple shapes (squares, circles, half-planes) and describe logically. Like a point in the area, if it is in figure A, but not figure B; or in figures C and D, or in figures E and E.
Further to translate this into code is one if with a bunch of conditions combined with logical or ( ||) or logical AND ( &&).