$(6)$ A brick $($dimensions $8in.4in.2\mathrm{.}5in.)$ is compressed by a force $P,$ as shown in Figure $6.$ If the allowable shear stress for brick is $1200$ psi and the allowable compressive stress is $3600$ psi, what force $P_{\text{m}\text{a}\text{x}}$ is required to break the brick?