Which biconditional is not a good definition? a. a whole number is even if and only if it is divisible by 2. b. a whole number is odd if and only if the number is not divisible by 2. c. an angle is straight if and only if its measure is 180. d. a ray is a bisector of an angle if and only if it splits the angle into two angles.

Option D.

Step-by-step explanation:

A biconditional statement are the statement in which both parts have the same truth value. It is written in the form of "p if and only if q".

First statement: A whole number is even if and only if it is divisible by 2.

This statement is a biconditional statement because it is the definition of even numbers and have the same truth value.

Second statement: A whole number is odd if and only if the number is not divisible by 2.

This statement is a biconditional statement because it is the definition of odd numbers and have the same truth value.

Third statement: An angle is straight if and only if its measure is 180.

This statement is a biconditional statement because it is the definition of straight angle and have the same truth value.

Fourth statement: A ray is a bisector of an angle if and only if it splits the angle into two angles.

This statement is not a biconditional statement because if a ray splits the angle into two angles, then it is not necessary that it is a bisector.

Definition of bisector: A ray is a bisector of an angle if and only if it splits the angle into two congruent angles.

Therefore, the correct option is D.

b

step-by-step explanation: