12.10 Standing waves are produced by the superposition of two waves, \begin{equation*} y_1 = 7 \sin \left( 2\pi \left( \frac{t}{T} - \frac{2x}{\pi} \right) \right) \end{equation*} and \begin{equation*} y_2 = 7 \sin \left( 2\pi \left( \frac{t}{T} - \frac{2x}{\pi} \right) \right) \end{equation*} traveling in opposite directions. Find (a) the amplitude, (b) the wavelength $\lambda$, (c) the length of one loop, (d) the velocity of the waves, and (e) the period.