Question

I need helppp!! This is confusing !

Answer 1

mCD = 9

Explanation:

Because this polygon has opposite parallel sides, meaning each side across from each other are parallel, we know that this is a parallelogram. So:

AB ║ DC

BC ║ AD

Because this is a parallelogram, we know that, from the properties parallelograms, opposite sides of a parallelogram are congruent. This means that AB ≅ DC.

This also means that because AB = 9 and AB = DC, DC = 9.

Here's a mini two-column proof:

Statements → Reasons

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

mAB = 9 → Given

AB ║ DC, BC ║ AD → Given

ABCD is a parallelogram → Definition of a Parallelogram

AB ≅ DC → Opposite sides of a parallelogram are congruent.

mAB = mDC → Definition of Congruent Segments

9 = mDC → Substitution Property of Equality

mCD = mDC → Reflexive Property of Equality

mCD = 9 → Substitution Property of Equality

Answer 2

9

Explanation:

So the little arrows on the lines means they are equal to each other so if you look, A to D and B to C have only one arrow meaning those two lines are the same lines

and A to B and D to C have two arrows meaning those two lines are the same

so that means if A to B is 9 and it's equal to the line D to C, then D to C is also 9

Hopefully this wasn't too confusing