FP1 Parabolas help?

a) Find the equation of the tangent at the point P(4a,4a) to the parabola with equation y²=4ax.

The tangent meets the x axis at point R(-4a,0) and the second tangent to the parabola with equation y²=4ax from R meets the parabola at Q(4a,-4a).

b) Calculate the area of the finite region enclosed between the tangents RP, RQ and the parabola with equation y²=4ax.

For a), I've found the equation of the parabola to be x-2y+4a=0.

I'm stuck on b). I've found the area of the triangle PQR by doing the following calculation:
0.5x8ax8a=32a². I'm not sure what to do from there..?

What you've found so far is the area of the isosceles triangle with equal sides RP, RQ and base 8a.

Since you're finding the area enclosed between the tangents and the parabola, you need to subtract the area between the parabola and x-axis from the triangle to obtain the correct answer.

That's the bit I'm not sure how to do- how do I find the area between the parabola and the x axis?

Also, is this diagram correct (the red bit being the area I need to find)