so, for this task:
- a parallelogram is not a rectangle or a square
- a kite is not a rhombus or an arrowhead
- a rhombus is not a square
- a trapezium is not an isosceles trapezium
establishing that you have found the largest possible shape (in terms of area) is not that easy...
question 10 has an 'easy' answer that it is incorrect (with sides of length (root 5) and 2)!
many thanks to Fawn Nguyen for producing her own (neat and US-friendly) version of this task
see the related task from Math Pickle
my solutions have these areas
(questions 21, 22 and 24 have two congruent shapes that will work)