What is the name of a shape that has a perimeter of 12 cm and an area of 6 sq cm.?

There are many such shapes, for example:

• A rectangle of length 3+√3 cm (≈ 4.732 cm) and width 3-√3 cm (≈ 1.268 cm);
• An L shaped hexagon with side lengths (in order) 4 cm, 2 cm, 2 cm, 1 cm, 2 cm, 1 cm (the internal angles between the sides are 90°, 90°, 90°, 270°, 90°, 90° in order);
• An octagon with side lengths (in order) 3 cm, 1 cm, 1 cm, 1 cm, 3 cm, 1 cm, 1 cm, 1 cm (with internal angles 90°, 270°, 90°, 90°, 90°, 270°, 90°, 90°).
• A T shaped octagon with side lengths (in order) 2 cm, 1 cm, 1 cm, 1 cm, 4 cm, 1 cm, 1 cm, 1 cm (with internal angles 90°, 270°, 90°, 90°, 90°, 90°, 270°, 90°).