It's not quite clear what's your question is actually asking but in general squares and rectangles consist of parallel and perpendicular line whereas right angle triangles have only perpendicular lines which meet at 90 degrees.
It could be a trapezoid
A shape that has two parallel lines and no perpendicular lines is a trapezoid, specifically an isosceles trapezoid. In this shape, one pair of opposite sides is parallel, while the other pair is not perpendicular to the parallel sides. This creates a unique geometry without right angles. Another example could be a parallelogram, which also has two pairs of parallel sides but does not necessarily have any perpendicular lines.
They could be: parallel lines, perpendicular lines or intersecting lines
It could be a right angle triangle
Not necessarily. It could be a pentagonal based pyramid.
It could be a trapezoid
If you are sitting in a room, the ceiling and the floor are parallel to each other. The walls are perpendicular to the floor and to the ceiling. So any line on these surfaces will be parallel to or perpendicular to any line on the other surface. And if they were not, the building could be quite unstable.
They could be: parallel lines, perpendicular lines or intersecting lines
Parallelogram and a rectangle
Two lines are said to be parallel if perpendicular distance between them is always constant. Length of a pair of parallel lines need not to be same. It can be different.
If the field lines were not perpendicular to the surface, then they could be decomposed into components perpendicular and parallel to the surface. But if there is an E-field along the surface, the surface is no longer an equipotential.
A circle.
It could be a right angle triangle
Not necessarily. It could be a pentagonal based pyramid.
The only requirement for a trapezoid is that one pair of opposite sides be parallel. There could be trapezoids with a pair of perpendicular lines.
Parallelogram and a rectangle
It could be a square or a rectangle