trig/geometry question 2001 9 a ii (1 Viewer)

[crammy90]

so i can get a i and i could eventuall do ii from just changing the different sides around as ratio's untill i got the needed equation. When we are doing this ii does every1 just trial and error with the corresponding sides of the similiar triangles untill they end up with the needed equation?
is there anyother way to do it cuz its time consuming...