ANSWER

EXPLANATION
The given parabola has directrix x=2.
This implies that, the parabola is opens in the direction of the negative x-axis because it must open in a negative direction to the directrix.
The equation of such parabola is of the form:

where (h,k)=(-5,8) is the vertex.


But the parabola opens to the left.
p=-7
The equation now becomes


Look at the picture.
To find the area of triangle DBC we need to find its base, x, and its height, h.
Triangle ABC is a right triangle, so using the Pythagorean theorem we can find x.

Now look at triangles ABC and DBH. They both are right triangles and have the same angle α. That means they're similar and their corresponding sides are proportional. The ratio of the side opposite to angle α to the hypotenuse is the same in both triangles - so the ratio of h to 1 is the same as the ratio of 3 to 5.

The base x is 4, the height h is 3/5. Calculate the area:

The area of triangle DBC is 6/5.
Equal because these numbers are of the same value
I am attaching a document showing the steps.