Answer:
54
Step-by-step explanation:
to evaluate substitute b = 18 into 3b
3b = 3 × 18 = 54
We know that the law of sines states that:

For simplicity, let:

In triangle A1BC this leads to:

Therefore:

Now, triangle A2BC is isosceles which means that both the base angles are equal, since angle CA1B and A2A1B are supplementary we have: