even though the increased protection to a point, provided by angling a certain armour plate with a given normal thickness causing an increased line-of-sight ("los") thickness, is of no consideration in armour vehicle design, it is of great importance when determining the level of protection of a designed vehicle. the los-thickness for a vehicle in a horizontal position can be calculated by a simple formula, applying the cosine rule: it is equal to the armour's normal thickness divided by the cosine of the armour's inclination from perpendicularity to the projectile's travel (assumed to be in the horizontal plane) or: