c²=5²+8²-2*5*8*cos120=25+64-2*40*(-1/2)=89+40=129
c=√129
d²=5²+8²-2*5*8*cos60=25+64-2*40*1/2=89-40=49=7²
d=√7
c²=5²+8²-2*5*8*cos120=25+64-2*40*(-1/2)=89+40=129
c=√129
d²=5²+8²-2*5*8*cos60=25+64-2*40*1/2=89-40=49=7²
d=√7