Such shapes are known as symmetrical.
An isosceles triangle has one line of symmetry
An isosceles triangle has one line of symmetry
a heart
Trapezium
A symmetrical shape. There are many different shapes that have one or more lines of symmetry and there is no other name associated with them as a group.
the shape is a heart.
scalene triangle.
Isosceles triangle
a pentagon
An irregular pentagon.
You cannot have one parallel line. There must be another line that it is parallel to. Also, 1 symmetry is meaningless - you can have one axis of symmetry or rotational symmetry of order one. The answer will depend on which one it is.
well it has 1 line but it depends on the shape of the rhombus