At the part where you said "4/3 (3.1416)(216)" you are suppose to actually multiply 4/3(3.14)(216) Not "3.1416". Because when you multiply "4/3(3.14)(216)" you get 904.32 which is rounded to 904.3.
<span>ΔABC, ΔDEF, and ΔGHI </span> I think all triangles are congruent. 2 sides and 1 angle of each triangle is has the same measure. Making these triangles congruent in SAS theorem.