Diketahui luas segitiga ABC pada gambar berikut 66cm². Keliling segitiga ABC adalah...

Luas = 1/2 x AB x CD
66 = 1/2 x AB x 12
66 = 6AB
AB = 11 cm

AC² = AD² + CD²
AC² = (11 + 5)² + 12²
AC² = 16² + 12²
AC² = 256 + 144
AC² = 400
AC = √400
AC = 20 cm

BC² = BD² + CD²
BC² = 5² + 12²
BC² = 25 + 144
BC² = 169
BC = √169
BC = 13 cm

K = AB + BC + AC
K = 11 cm + 13 cm + 20 cm
K = 44 cm