4 In a triangle \(A B C , A B = 5 \sqrt { 2 } \mathrm {~cm} , B C = 8 \mathrm {~cm}\) and angle \(B = 60 ^ { \circ }\).
- Find the exact area of the triangle, giving your answer as simply as possible.
- Find the length of \(A C\), correct to 3 significant figures.