9 In the parallelogram ABCD (AB || CD and AD || BC), E is on BC. AE cuts the diagonal BD at G and the line DC at F. Denote AG = a and GE = b and EF = x. a Prove that AFDG ~ AABG and ABGE ~ ADGA. Hint: Use the alternate interior angles determined by the parallel sides of the parallelogram ABCD. b) Use a) to determine x in terms of a and b. Hint: Use the similarity proportions implied by the two pairs of similar triangles at a)