Question 11 Multiple Choice Worth 4 points)
(02.06 MC)
Look at the quadrilateral shown below
Melissa writes the following proof for the theorem. If the diagnosis of a quadrilateral bisect each other, the quadrilateral is a parallelogram.
Malissa's proof
1. For trangles $\mathrm{AOB}$ and $\mathrm{COD}$, angle 1 is equal lo angla 2, as they are vertical angles.
2. $\mathrm{AO}=\mathrm{OC}$ and $\mathrm{BO}=\mathrm{OD}$ because it is given that diagonals bisect each other.
3. The are congruent by SAS postulate.
4 Similarly, triangles AOD and $C O 8$ are congruent.
5. By CPCTC, As is equal to DC.
6. By CPCTC, AD is equal to BC.
7. As the opposite sides are congruent, the quadrilateral ABCD is a parallelogram.
Which is the mussing phrase in Melissa's proof?
angles ADE and CED
angles AOP and COO
triangles ADB and CBD
triangles AOB and COO