3 The diagram shows a triangle \(A B C\).
\includegraphics[max width=\textwidth, alt={}, center]{bfe96138-9587-4efb-95c5-84c4d5eadfbe-3_273_622_356_708} The lengths of \(A C\) and \(B C\) are 5 cm and 6 cm respectively.
The area of triangle \(A B C\) is \(12.5 \mathrm {~cm} ^ { 2 }\), and angle \(A C B\) is obtuse.

1. Find the size of angle \(A C B\), giving your answer to the nearest \(0.1 ^ { \circ }\).
2. Find the length of \(A B\), giving your answer to two significant figures.