Yang no 6 nya dong please

ec² = 15²-9²
itung sndiri nt
ec = 12

∆abc dan ∆ced sebangun
ec ~ bc
ed ~ ab
bc = 15+bd
ec / ed = bc / ab
12 / 9 = 15+bd / 12
9(15+bd) = 12 . 12
135 + 9bd = 144
9bd = 144-135
9bd = 9
bd = .....