Use the appropriate reciprocal identity to find the exact value of $\sin \theta$ for the given value of $\csc \theta$. Rationalize denominators when applicable. \[ \csc \theta=\frac{\sqrt{63}}{7} \] \[ \sin \theta= \] (Simplify your answer, including any radicals. Use integers or fractions for any numbers in the expression.)

Step 1 ：We are given that \(\csc \theta = \frac{\sqrt{63}}{7}\)

Step 2 ：We know that the reciprocal identity for sine and cosecant is \(\sin \theta = \frac{1}{\csc \theta}\)

Step 3 ：So, to find the value of \(\sin \theta\), we need to take the reciprocal of the given value of \(\csc \theta\)

Step 4 ：\(\sin \theta = \frac{1}{\frac{\sqrt{63}}{7}} = \frac{7}{\sqrt{63}}\)

Step 5 ：We simplify the above expression to get \(\sin \theta = \frac{\sqrt{7}}{3}\)

Step 6 ：Final Answer: \(\sin \theta = \boxed{\frac{\sqrt{7}}{3}}\)