Question

Segitiga DEF mempunyai keliling 70 cm. Jika panjang sisi EF = 25 cm dan DF = 17 cm, berapakah luas segitiga tersebut? (beserta cara)

Answer 1

Keliling = 70 
S = 1/2 keliling = 1/2 (70) = 35
EF = d= 25
DF = e= 17
DE = f =  70 - EF - DF = 28

L =√{s(s-d)(s-e)(s-f)
L = √{ 35 (35-25)(35-17)(35-28)}
L = √(35)(10)(18)(7)
L = √(5 x 7 x 5 x 2 x 2 x 9 x 7)
L = √(5² x7² x2² x 3²)
L= 5 x 7 x 2 x 3
L= 210 cm²