Cosine and sine rules in a quadrilateral made of two triangles, with the ambiguous case for a second point

In the diagram, \(PQ=8\text{ cm}\), \(PR=6\text{ cm}\) and \(\angle QPR=50^\circ\). The point \(S\) lies on the other side of \(QR\) from \(P\), where \(\angle SQR=35^\circ\) and \(\angle QRS=75^\circ\). Give each answer correct to \(3\) significant figures.

1. Find \(QS\).[4]
2. Find the area of the quadrilateral \(PQSR\).[3]
3. The point \(T\) lies on \(QR\) such that \(ST=SR\) and \(T\) is not the same point as \(R\). Find \(RT\).[3]