Define Pressure on an Inclined Plane

Similar to a vertical plane, fluid pressure increases linearly with increasing depth. The average pressure on an inclined plane occurs at the average vertical depth. If angle σ is provided along with inclined dimensions measured from the fluid surface to the top of the inclined plane (h₃), and from the fluid surface to the bottom of the inclined plane (h₄), use trigonometry to determine the vertical dimensions (h₁) and (h₂)

Average P = ½ (ϒ) (h₁+h₂)

Average P = ½ (ϒ) (h₃+h₄) sin σ