tentukan panjang AB!

cari dulu be
bc/ac = ec/dc
(10+be)/12= 10/8
8(10+be) = 10 x 12
80+8be = 120
8be= 120 - 80
8be= 40
be= 5 cm

bc = be+bc =10 + 5 = 15 cm

ab= √(bc² - ac²)
ab = √(15² - 12²)
ab = √(225 - 144)
ab = √81
ab = 9 cm