tolong dibantu no 40, makasih ya :)

c 7 3/5...
maaf kalo salah

CE = √BC^2 - BE^2
= √10^2 - 6^2
= √100-36
= √64
= 8
CE/BF = BC/AB
8/BF = 10/9
10BF = 8 x 9
10BF = 72
BF = 72/10
= 36/5
= 7 1/5 (A)