Question

Glven: ABCD is a parallelogram. Prove: AB - CD and BC – DA

Answer 1

Answer:

$by \: rotation : \\ { \bf{AB + BC = CD+ AD}} \\ { \boxed{ \tt{AB - CD = BC - DA}}}$

since: DA = -AD

Answer 2

Answer:

Here are all the answers (this took me awhile to figure out myself)

Step-by-step explanation:

Statement 1: ABCD is a parallelogram.

Reason 1: Given

Statement 2: draw AC.

Reason 2:  Unique line postulate.

Statement 3: BCA & DAC are alt. interior angles.

Reason 3: def. of alt. interior angles.

Statement 4: DCA & BAC are alt. interior angles.

Reason 4: def. of alt. interior angles.

Statement 5: AB || CD

Reason 5: def. of parallelogram

Statement 6: BC || DA

Reason 6: def. of parallelogram

Statement 7: <BCA = <DAC

Reason 7: alternative interior angle theorem

Statement 8: <DCA = <BAC

Reason 8: alternative interior angle theorem

Statement 9: AC = AC

Reason 9: reflexive property

Statement 10: ABC = CDA

Reason 10: ASA

Statement 11: AB = CD

Reason 11: CPCTC

Statement 12: BC = DA

Reason 12: CPCTC