<Qua-2024-733>, hint

a>,Let M be the midpoint of BD, then [ABCM]=[ADCM] 

b>. In trapezoid ABCD, AB//CD, BC=DA, Let M,N be the midpoints of AB, CD. 

Consider a point P such that AB/CD=NP/MP

Then [PBS]=[PAD], [PAB]=[PCD]

c>. a parallelogram