an angle with a acute and right angle
A right angle triangle
a right angle triangle.
A right angle triangle
A right (angled) triangle.
There is no special name for such a shape.
There is no special name for such a shape.
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.
It is a triangle
a rectangle
a square
d