Answer:
4.9 units
Step-by-step explanation:
Use the cosine rule for the triangle ABC:
[tex]a^2=b^2+c^2-2bc\cos\angle A,\\ \\a^2=7^2+3^2-2\cdot 7\cdot 3\cdot \cos37^{\circ},\\ \\a^2\approx 49+9-42\cdot 0.798,\\ \\a^2=58-33.516=24.484,\\ \\a\approx 4.9\ un.[/tex]
