Answer:
29° , 121° or ≈ 30° and ≈ 120°
Step-by-step explanation:
Law of cosine: a² = b² + c² -2bc cos A
a² = 16 + 49 - 2 x 4 x 7 x cos30° = 16.5
a = 4.1
Law of sin: smaller angle 4 / sin ∠BCA = 4.1 / sin 30°
sin ∠BCA = 0.49
∠BCA = 29° (≈30°)
∠ABC = 180 - 29 - 30 = 121° (≈120°)
