An arrow head
A reflex angle
An arrowhead
A four-sided shape with one right angle is a quadrilateral. There is no more specific term, unless it has more than one right angle or has equal sides.
There is no special name for such a shape.
It is an irregular quadrilateral. It cannot have any parallel sides.
It can, but does not have to.
No. For a start, a circle has no angles. No regular polygon has a reflex angle.
An arrowhead
A reflex angle
A four-sided shape with one right angle is a quadrilateral. There is no more specific term, unless it has more than one right angle or has equal sides.
There is no special name for such a shape.
There is no special name for such a shape.
parallelogram!
a rectangle
It is an irregular quadrilateral. It cannot have any parallel sides.
In plane geometry, a shape with four sides, two of which are parallel and have the same length, cannot have a reflex angle.
cheesse