Height of the trapezoid, i.e. the distance between the sides \( a \) and \( b \).
The angle enclosed by the sides \( c\) and \( a \). Alternatively, the trapezoid height can be expressed with the angle \( \beta \). This is the angle enclosed by the sides \( d\) and \( c \):\[ h ~=~ d \, \sin(\beta) \]
Length of the corresponding side of the trapezoid (see illustration). If \( c = d \), then the trapezoid is isosceles.