How to find out if a point is in a given area?

Question

PHP

Good afternoon!
The administrator on the client using Yandex Maps allocates a zone. A zone is created using a polyg and a set of points is sent to the server.
An example of a set of points:

[]

Further, a request with its coordinates arrives on the back from the user and the following task is set: Determine whether the coordinate falls into the specified area.
How to do it?