Boundary Values & Fourier Series · Easy problem

A string satisfies $u_{tt} = 9u_{xx}$ for $0 < x < \pi$ with fixed ends $u(0,t) = u(\pi,t) = 0$, initial shape $u(x, 0) = \sin 2x$ and initial velocity $u_t(x, 0) = 0$. Find $u\!\left(\dfrac{\pi}{4}, \dfrac{\pi}{18}\right)$.