### Theory:

A triangle is a polygon with three vertices, three edges and three angles.
Let us recall some basic notations of a triangle $$ABC$$.

In the above triangle $$ABC$$:
• $$A, B$$ and $$C$$ are vertices.
• $$a, b$$ and $$c$$ are edges (side lengths).
• $$x, y$$ and $$z$$ are angles.
Example:

In the above triangle $$ABC$$:
• $$A, B$$ and $$C$$ are vertices.
• $$8$$ units, $$5$$ units and $$5$$ units are the side lengths.
• $$94°, 43°$$ and $$43°$$ are interior angles.