Answer:
BC= 14.6
Step-by-step explanation:
The law of cosines tells you ...
BC² = AB² +AC² -2·AB·AC·cos(A)
BC² = 9² +12² -2·9·12·cos(87°) ≈ 213.695
BC ≈√213.695 ≈ 14.6
The length of BC is about 14.6 units.
