Rhombus
It is convex if you look at it from the inside but it is not any kind of polygon.
I think it's congruent.
The word polygon means a many sided plane figure or shape. Triangles, squares, pentagons and so on are all polygons. A Parallelogram is a special kind of 4-sided figure and is a polygon.
All triangles have 180 degrees, all quadrilaterals have 360 degrees, no matter what the kind of triangle or quadrilateral. The formula would hold true for all polygons. Prove this by drawing diagonal lines in a polygon (do not cross one diagonal with another) to divide the polygon into quadrilaterals and/or triangles. Then add the degrees in the quadrilaterals and triangles in your polygon. This should give you the correct number of degrees. If you have a many sided polygon, it is necessary to use the formula, because the figure would be very difficult to draw. Formula- Number of sides minus 2, times 180 degrees. (n-2) X 180= degrees in a polygon
depends on what size triangles and what kind of triangles?
They can be any kind of triangles.
a pyramid can use any triangles possible.
Right-Angle triangles
It is not a polygon, because a polygon is a closed figure.
It is a convex polygon.
inscribed polygon
A regular polygon.