<-- a
<-- b
<-- c
<-- d
<-- angle 1 α
<-- angle 2 γ
  

The following practice problem has been generated for you:
Given a quadrilateral with sides a = 11, b = 11, c = 7, and d = 7 with opposite angles α = 30 and γ = 30, calculate the area using Bretschneider's formula