$5\mathrm{.}12-12$ Aflying buttress transmits a load $P=25kN,$

acting at an angle of $60$ to the horizontal, to the top

of a vertical buttress $AB($see figure$).$ The vertical

buttress has height $h=5\mathrm{.}0m$ and rectangular cross

section of thickness $t=1\mathrm{.}5m$ and width $b=1\mathrm{.}0m$

PROBLEM $5\mathrm{.}12-12$