Question

Deci dau coroana va rog ajutati-mă!!!

Answer 1

Explicație pas cu pas:

mECB=mCBA(=60)

CB secanta

=> CE//AB

mEDC=60 =>mBDE=120

BD=DE (DC=ED=BC/2) => mDEB=mDBE=30°

=> mCEB=90 si CE//AB => ABEC tr. dr.

AB=12cm => EC=6cm

Fie CM_|_AB => CM=lV3/2=12V3/2=6V3

A ABEC=(EC+AB)*CM/2=18*6V3/2=54V3cm²

mABC=60 => mDBG=120

BD=6cm si BG=6cm => Triunghiul DBG isoscel =>

mBGD=mBDG=30

DF_|_AC si mACD=60 =>mFDC=30

cum mFDC=mBDG, mADF=mCDG=180-30 si B,D,C coliniare => BDG op. la vf. cu FDC <=> G,D,F coliniare