To determine if the biconditional statement is valid, let's break it down:

The statement says:
"Two angles form a linear pair if and only if they are supplementary."

A biconditional statement means both the forward and reverse implications must be true. Let’s analyze both:

1. Forward direction (if two angles form a linear pair, then they are supplementary):

   • A linear pair consists of two adjacent angles whose non-common sides form a straight line. This implies the sum of their measures is $180^\circ$, making them supplementary.
   • This part is true.

2. Converse direction (if two angles are supplementary, then they form a linear pair):

   • Two angles are supplementary if their measures add up to $180^\circ$. However, supplementary angles do not have to be adjacent or form a linear pair. For example, two angles can be supplementary but non-adjacent (not forming a linear pair).
   • This part is false because supplementary angles don't need to be adjacent.

Conclusion:

The biconditional statement is not valid because the converse is false (you can have non-adjacent supplementary angles).

The correct answer is:
2. Not Valid, Converse is false b/c you can have non-adjacent supplementary angles.

---

Would you like more details or have any questions?

Here are 5 related questions to expand your understanding:

1. What is the difference between adjacent and non-adjacent angles?
2. Can two complementary angles be non-adjacent?
3. How can we represent supplementary angles on a coordinate plane?
4. What are some real-world examples of linear pairs?
5. Is it possible for two obtuse angles to form a linear pair?

Tip: When dealing with biconditional statements, always check both the forward implication and its converse.