Answer:
b = 31 in
Explanation:
You want the length of side b in ∆ABC with B = 150°, C = 20°, c = 21 in.
Law of sines
The law of sines tells us ...
b/sin(B) = c/sin(C)
b = c·sin(B)/sin(C) = (21 in)·sin(150°)/sin(20°) ≈ 31 in
The length of side b is about 31 inches.
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