Keliling segitiga ABC adalah ..cm

BC = AC = 15 cm
AD = DB = √15^2 - 12^2 = √225 - 144 = √81 = 9 cm
AB = AD + DB = 9 + 9 = 18 cm

Keliling = 15+15+18 = 48 cm

AC = BC = 15 cm

AD = BD = √15² - 12²
AD = BD = √225 - 144
AD = BD = √81
AD = BD = 9 cm

AB = AD + BD
AB = 9 cm + 9 cm
AB = 18 cm

K = AC + AB + BC
K = 15 cm + 18 cm + 15 cm
K = 48 cm (D) ✔