Răspunsuri

2014-04-21T15:27:48+03:00
DinΔABD ,∧B=30 ∧BAD=60⇒cateta care se opune unghiului de 30 de grade=1/2 din ipoetnuza⇒AB=AD.2=40 cm
aplicam Pitagora in ΔADB⇒BD²=40²-20²=1600-400=1200
BD=20√3 cm
th inaltimii ⇒AD²=BD.DC
400=20√3×DC
DC=400/20√3=20√3/3
A= BC×AD/2= (20√3+20√3/3)×20/2=800√3/3 cm²
2 3 2