$($N$10$B$\mathrm{.}8)$ A pendulum of length L hangs vertically at rest. You pull it to the right until it makes an angle of $0=15$ at t $=0$ with respect to the vertical, then release it$.$ It swings back and forth with a period of exactly $1\mathrm{.}0$s$,$ and you model its angular

motion as $($t$)=$A cos $($ t $+$ $),$ where $=$What are L$,$ A$,$ and $?$