Geometry

Question Analysis
This question involves identifying the incorrect 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."
If either part is false, the biconditional statement is incorrect.

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 rectangle, then it has four right angles and opposite sides are equal. (True)
Converse: If a quadrilateral has four right angles and opposite sides are equal, then it is a rectangle. (True)
This is a valid biconditional statement.

Option B:
Original: If a triangle is scalene, then it has no equal sides. (True)
Converse: If a triangle has no equal sides, then it is scalene. (True)
This is a valid biconditional statement.

Option C:
Original: If an angle is straight, then it measures exactly 180°. (True)
Converse: If an angle measures exactly 1...