### Theory:

Tetrominoes, in general, are classified into different types based on the alignment of the four-unit squares present in it. They are orthogonal.
Based on the alignments the tetrominoes are classified into five base types namely,
• Straight-Tetromino
• Square-Tetromino
• $$L$$-Tetromino
• $$Z$$-Tetromino
• $$T$$-Tetromino
Rotational Properties of Tetrominoes:
• We represent these five tetrominoes in various ways based on their angle of rotation.
• When we rotate the tetrominoes in $$90$$ degrees clockwise or anti-clockwise direction, it begins to produce different projections of their base types
• Even if we rotate tetrominoes to different angles, they remain at their same base type.
• Some tetrominoes exhibit Rotational-Symmetry.
Rotational-Symmetry is the property a shape has when it looks the same after some rotation by a partial turn, and it is the number of distinct orientations in which it seems the same for each rotation.
The different tetrominoes obtained after angular rotations are given below:

Straight-Tetromino:
• The Straight-Tetromino exhibits $$2$$fold Rotational-Symmetry. That is, the Straight-Tetromino obtains the same shape $$2$$ times while undergoing a rotation of $$90$$ degrees till it reaches the original shape.

Square-Tetromino:
• The Square-Tetromino exhibits $$4$$fold- Rotational-Symmetry. That is, the Square-Tetromino obtains the same shape $$4$$ times while undergoing a rotation of $$90°$$ till it reaches the original shape.

L-Tetromino:

Z-Tetromino:

• The Z-Tetromino exhibits $$2$$fold - Rotational-Symmetry. That is, the $$Z$$-Tetromino obtains the same shape $$2$$ times while undergoing a rotation of $$90°$$ till it reaches the original shape.
•

T-Tetromino: