The first question is to connect CD and BE to O, ∴∠ ebo+∠ BeO = ∠ OCD+∠ ODC. ∠ FBD = ∠ ebo+∠ BeO is in a triangle BEF, and the sum of internal angles is =/kloc-0.

So the sum of the internal angles of the two triangles = 360.

The second problem is Pythagorean theorem, AC = 5s = 1/2axbc = 30.

Equal product formula, CDxAB=ACxBC, ∴CD= 60/ 13.

∫ is the center line, ∴SABE= 1/2 SABC = 15.

△dbf∽△abc,∴df/ac=db/ab df/5 = 1 1/ 13 ∴df=55/ 13

Hope to adopt