ducem inaltimile DE si CF _I_ pe AB
EF=27 cm
AE=x
FB=y
DE=CE=h
in triunghiul ADE h²=15²-x²
in triunghiul BCF h²=20²-y²
225-x²=400-y²
y²-x²=175
(y-x)(y+x)=175
x+y=52-27=25
y-x=175/25=7
2y=25+7=32
y=16 cm
x=y-7=16-7=9 cm
CF=h=√(15²-x²)=√(15²-9²)=√(225-81)=√144=12 cm
AF=AB-FB=52-16=36
AC=√(CF²+AF²)=√(12²+36²)=√(144+1296)=√1440=12√10 cm