need help in tis problem
posted by janika .
which biconditional is not a good definition?
1. a whole number is odd if and only the number is not divisible by 2
2. an angle is straight if and only if its measure is 180
3. a whole number is even if and only if it is divisible by 2
4. a ray is a bisector of an angle if and only if it splits the angle into two angles
need help in tis problem -