A contractor is required to prepare a soil surface so that it is planar and the normal d...

A contractor is required to prepare a soil surface so that it is planar and the normal direction to the surface is within 0.5^o of vertical. If the elevations at points A and B, relative to the elevation at point C, are -3.3 ft and -4.2 ft, respectively, determine the angle between the soil surface’s normal direction and the vertical, and if the surface is sufficientl level.