posted by kud
Shopping centers X, Y and Z are such that Y is 12 km south of X and Z is 15 km from X. Z is on a bearing of 330° from Y.
ok. Draw your diagram and say what it is you want to know.
If you want the distance from Y to Z, then use the law of sines.
sin30/15 = sinZ/12
Now you have angles y and Z so you can find X.
The law of cosines then tells you that
x^2 = 15^2+12^2-2*15*12 cosX