A shape with three and only three sides is a triangle, but it is not possible for a triangle to have three perpendicular sides.
Any polygonal shape, other than a triangle can have perpendicular lines.
triangle.
equilateral triangle
A right angled triangle is an example of a shape with exactly 2 perpendicular sides.
Not necessarily. It is a plane shape which could be horizontal.
The first geometric shape that comes to mind with no perpendicular sides is a triangle.
A right angle triangle.
Yes its perpendicular height or altitude is sometimes calculated out side the triangle depending on its shape.
Any shape, other than a triangle can have a pair of perpendicular sides.
converse of the perpendicular bisector theorem
A right angled triangle.