Geometry

Question Analysis
This question involves identifying the correct biconditional statement.
The main focus is on verifying the logical validity of each statement.

Key Concept Explanation:
A biconditional statement requires both the original statement and its converse to be true, linked by "if and only if."

Step-by-Step Solution:
Analyze each option to determine if both the original statement and its converse are true.

Option A:
Original: If a quadrilateral is a square, then it has four equal sides. (True)
Converse: If a quadrilateral has four equal sides, then it is a square. (False, it could be a rhombus)
This is not a valid biconditional statement.

Option B:
Original: If a triangle is isosceles, then it has two equal sides. (True)
Converse: If a triangle has two equal sides, then it is isosceles. (True)
This is a valid biconditional statement.

Option C:
Original: If an angle is right, then it measures less than 90°. (False, right angles measure exactly 90°)
Converse: If an angle measures less than 90°, then it is...