A Triangle~!
A square or a rectangle.
no
An irregular pentagon.
Well, honey, that's a right triangle. It's like a regular triangle, but with a sassy little right angle thrown in there to keep things interesting. So, if you're looking for a shape that's all about that right angle life, you've found it.
Right triangle
A right-angle triangle.
A right angled triangle.
A square or a rectangle.
a ploygon or quadrilateral
no
A rhombus.
Rhombus, trapezoid, parallelogram
triangle
an "irregular pentagon"
a trapezoid
trapezoid
It could be a right angle triangle