Which statement about the central ray in bisecting-angle technique is true?

• A. It is directed toward the image receptor
• B. It is parallel to the tooth root
• C. It is perpendicular to the bisected angle
• D. It is perpendicular to the image receptor

Answer: (C)

In the bisecting-angle technique, the key idea is geometry: you aim the X-ray beam so that it is perpendicular to the line that bisects the angle formed by the tooth and the image receptor. This positioning makes the beam strike the tooth and receptor at equal angles, which minimizes distortion because the projection is as true to life as possible given the receptor isn’t parallel to the tooth. If the beam were directed strictly toward the receptor or kept perpendicular to the receptor, you’d be following rules from other techniques, not this one.