for r 10A i made y the subject and found the unshaded area and minused it by the area of the triangle, to get the shaded area. i think it's right.
for 10B i proved the trianlges were similar, and then used the corresponding sides are equal to rule to find the top side for the top triangle...
If you talked about the king lear thoroughly enough you'll be fine... to get those A's you need to thoroughly talk about the techniques so don't worry you'll be fine :D