se formeaza ΔAOB-isoscel
AO=OB=R=20
AB=32
fie OD_|_ AB =>d(O;AB)=OD
A ΔAOB= b*h/2= AB*OD/2= 32*OD/2= 16*OD
A ΔAOB= √p(p-a)(p-b)(p-c)
p=(a+b+c)/2= (20+20+32)/2= 72/2=36
A ΔAOB= √36*(36-20)(36-20)(36-32)=
=√6² *16 *16 * 4=
=√6² *4² *4² *2²=
= 6*4*4*2=
=192
A ΔAOD=192
A ΔAOD=16*OD
16*OD=192 =>OD=12 =>d(O;AB)=OD=12
