Find the length of line segment FC

Area of triangle ADB = 1/2 × BD×AE

                                  =28 units squared

Area of full parallelogram= 2(area of triangle ADB)

*(Diagonal of parallelogram divides the triangle into two congruent triangles or two triangles of equal areas)

Therefore, area of parallelogram ABCD = 28×2 =56 units squared

We also know that area of parallelogram is

base ×height

So

B×H=56

12 × H = 56

H= 56/12 OR 14/3

$\text{AREA[ABCD]=DC(FC)=AE(BD})$ $\color{#69047E}\large{\implies}$ $12\text{FC}=4(14)$ $\color{#69047E}\large{\implies}$ $\text{FC}=\dfrac{4(14)}{12}=\boxed{\dfrac{14}{3}}$