1. The problem is about proving that all angles formed by bisectors of angles are equal. 2. When an angle is bisected, it is divided into two equal parts. This means each formed angle is exactly half of the original angle. 3. The formula or rule used here is: If $\angle ABC$ is bisected by a ray $BD$, then $\angle ABD = \angle DBC = \frac{1}{2} \angle ABC$. 4. It is important to explicitly mention "half" or "divided by 2" because it clarifies the relationship between the original angle and the bisected angles. 5. Saying "the formed angles equal the big angle over 2" is mathematically precise and helps in logical proofs. 6. Therefore, mentioning that the formed angles are $\frac{1}{2}$ of the original angle is necessary for clarity and rigor in your proof.