Adjacent sides are perpendicular. Opposite sides are parallel.
It fits the description of a right angle triangle
It could be a right angle triangle
shape no pairs of perpendicular sides
The perpendicular adjacent sides in the triangle would be 3 sides. It is the basically horizonstal line next to a vertical line(perpendicular) if it was parallel adjacent then only two side of triangle /\ <-- parallel
In a square adjacent sides are perpendicular to each other and opposite sides are parallel to each other.
The question does not make any sense. "Adjacent" means next to. A shape cannot be next to itself, and if it is next to another shape, then you have two shapes. "perpendicular" means at right angles (or 90 degrees) to. Again, a shape cannot be perpendicular to itself.