Geometry Problem 942: Triangle, Circles, Circumcircle, Sagitta, Incircle, Excircle, Inradius, Exradius, Metric Relations. Level: High School, College, Mathematics Education

As illustrated, the measure of the inradius of triangle ABC is 7 and the measure of the exradius corresponding to AC is 20. Find the measure of the sagitta of arc AC corresponding to circumcircle O.