Explain why when naming a plane we cannot use three collinear points?

When we are talking about a plane we usually talk about two dimensional surface.But in the real world there is no two dimensional thing.

For example consider a rectangular piece of paper,it has length and breadth but it has thickness which we consider as negligible.

Similarly faces of cube or cuboid forms a two dimensional plane.

When we say this is a plane we say that this is a flat surface.Word sheet is a plane.

Now coming to your question  why when naming a plane we cannot use three collinear points?

The reason being that to determine whether it is a plane or not we take two points on that surface. If the line joining that two points completely lies on that surface we say that it is a plane.

Now to draw a unique line we need only two points, So taking three collinear points and then showing it is a plane is worthless.

As i have written plane is a two dimensional surface and line is of single dimension.

So,Likewise on a line there are infinite number of points, on a plane there are infinite number of lines and to determine a unique line we need only two points, so taking three collinear points on a plane through which only one line passes is out of consideration we just need only two points.

20

step-by-step explanation:

the inequality is:

250c+180g≥950

step-by-step explanation:

let c denotes the number of days in a week   miyoko worked as a cryptographer.

and g denotes the number of days in a week she works as a geologist.

now we are given that she earns $250 for every day she works as a cryptographer,and earns $180 for every day she works as a geologist.

now miyoko's goal is to earn more than $950 this week.

hence, the inequality could be represented as:

250c+180g≥950