^^he is right
see the pic
in 1st figure the ACD is not a staight line. hence both 1st and 2nd figures are not a triangle n then u cant use the triangle property to calculate the area. u will hav to calculate the area by summin the areas of smaller figures whic gives 32 sq cm in both figures
i wonder how that mit professor didnt see that
note: one mistake in fig, for triangle CDF angle=tan inverse of (DF/CF) = 21.8 DIGREES