Question 5 • Precalculus
By the sine rule, sin B / 60 = sin 40° / 45, so sin B ≈ 0.857. This gives two possible angles: B ≈ 59° or B ≈ 121°, since angles with the same sine can be supplementary. Using A + B + C = 180°, the corresponding values of C are about 81° and 19°. Therefore, both pairs listed in choice B are possible.
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