Question

Rog rezolvarea problemei 4

Answer 1

 ΔABC dreptunghic in A 
mas<B=60°=> mas<C=30° => (T.30.60.90) AB=BC/2.
daca E mijloc BC => DE=CE=BC/2.

in ΔABE cunoastem BE=AB=(BC/2) => ΔABE isoscel. 
dar in ΔABE exista mas<B=60° => ΔABE echilateral( conform definitiei)

mas<DAE=mas<A-mas<DAB 
mas<DAE=90-60
mas<DAE=30°