9. ABCD is a parallelogram. If E = f and m = f, express BC> DC> E5 and AC) in terms of f and )7. 10. If A, B, and C are three collinear points with B at the midpoint of AC, and 0 is any point not on the line AC, prove that 0111> + 06" = 253'. (Hint: E = 36.) 11. ABCD is a quadrilateral with [E = if, CD> = 2?, and AC> = 33c) f. Express 5 and BC> in terms of 3c) and 5