If it is a 2-dimensional figure, it is a polygon.
polygon: it refers to a figure that has closed sides and straight edges with more than 3 sides
A pentagon is a 5 sided, closed figure.
quadrilateral shape
no, a quadrilateral cant be curved because it is a closed STRAIGHT sided figure with four sides...
Pentagon
Hexagon
A heptagon is a seven-sided closed polygon.
no, but an eight sided figure you could use is an octagon. a figure 8 may be a figure and closed but, it has no sides and no line segments.
Yes every trapezoid is a closed 4 sided quadrilateral
A three sided closed plane figure (shape) is a triangle.
A quadrilateral