A 13-year-old male is referred to clinic after a sport’s physical examination completed at his school. He was told that his spine is curved and to follow-up with his primary care provider. The patient does endorse some mild, mid thoracic back pains. Otherwise, the patient is healthy and without any past medical nor surgical history. Physical examination reveals a positive Adam’s bend test. Xray images were obtained. The Cobb angle is measured by which of the following?