Answer
Sailing speed is $6.3\ \text{knots}$ at an angle of ${{50}^{{}^\circ }}$ to the $10\ \text{knots}$ wind.
Work Step by Step
With the help of the given polar coordinate, $\left( 6.3,{{50}^{{}^\circ }} \right)$ we can derive that the sailing speed is $6.3\ \text{knots}$ at an angle of ${{50}^{{}^\circ }}$ to the $10\ \text{knots}$ wind.
