Alevel further maths - vectorsWatch
I suggest you start by drawing a diagram and get an idea of what the shape APQC looks like and how it relates to the various vectors described.
Without doing any calculations, but using the information given about how these things relate (e.g. that P is where the line AB intersects π), draw a diagram showing all the points, the relevant lines, and the plane π (you can represent π as a simple line intersecting both AB and BC).
Once you do that, you should be able to see how to represent the quadrilateral as "a shape you know how to find the area of" minus "another shape you know how to find the area of".
Note that two opposite sides of the quadrilateral are parts of the lines AB, BC, so it isn't a parallelogram.
Thanks so much for the explanation, when I redrew the diagram I was able to get the answer! For part b, would k be 2 and 8.6 and am I missing any other values? I used the scalar triple product.