Step-by-step explanation:
By using cosine rules:
6/sin45° = b/sin90°
b = 6× sin45°/sin90°
b = 9.124(3d.p)
Also,
using Pythagoras theorm of right-triangle
b² = 6² + a²
9.124² = 6² + a²
83.247376 = 36 + a²
83.247376-36 = a²
47.247376 = a²
√47.247376 = a
6.874 = a
