How far apart are A and B (to the nearest yard)?

Question

Two points A and B are on opposite sides of a building. A surveyor chooses a third point C 76 yd from B and
102 yd from A,  with angle ACB measuring 55.6°.  How far apart are A and B (to the nearest yard)?

What formula would you use?

Answer 1

Using law of cos for this side-angle-side case, (76, 55.6, 102)

AB² =76²+102²-2*76*102 cos(55.6)

AB=86.144