Answer:168.75 squared
Step-by-step explanation: we know that the whole of the rectangle ( including the outline) is 225 cm squared
so half of this is 225 divide by 2 and that is 112.5
but we also have a right-angled triangle that is half the half rectangle so we do 112.5 divide by 2 and that is 56.25
to finish it off we ad 56.25 with 112.5 and that is 168.75