Online Geometry Problem 813: Right Triangle Area, Excircles, Cathetus, Tangency
Points, Quadrilateral Area. Level: High School,
SAT Prep, College,
Mathematics Education

The figure below shows a right triangle ABC
of area 30 with the excircles E_{c} and E_{a} tangent to AB and BC at D and F,
respectively. Find the area of quadrilateral ADFC.