1. ParallelogramIdentify the base (any one side).From a vertex opposite the base, draw a perpendicular line down to the base or its extension.The perpendicular line is the height.2. TriangleChoose one side as the base.From the opposite vertex, draw a perpendicular line to the base.The perpendicular line is the height.3. RhombusUse one diagonal as the reference.Draw a perpendicular line from a vertex to the opposite side (or its extension).That line is the height.Formula: Height = Area ÷ Base.