Answer:
Irregular polygon, Scalene Triangle, Convex.
Explanation:
Polygons are defined as 2-dimensional figures whose shapes are closed and whose sides are line segments.
Then:
Plot the points A(2,1), B(7,1),C(2,4).
You can observe in the graph attached that the polygon has three sides whose lenghts are different.
By definition, a polygon of three sides and three angles is called: "Triangle".
If the lengths of the sides of the triangle are different, then it is called "Scalene triangle". Therefore, this polygon is Irregular, because its sides and angles are not equal.
The interior angles of a triangle add up 180°. Therefore, this polygon is also Convex (It does not have any interior angle greater than 180°).