Parallelograms

For what values of a and b is the quadrilateral a parallelogram? a =​ (a)   and b =​ (b)  

In a parallelogram, if the length of one diagonal is 10 units, which of the following must be true about the other diagonal?

Preview: I can tell in the parallelogram that AB $$\cong$$ ​ (a)   and that AE $$\cong$$ ​ (b)   and that $$\angle BAD\ \cong\ \angle$$ ​ ​ (c)   .

Refer to parallelogram ABCD. LABEL what angle BCD should be.

Find the value of each variable in the parallelogram.

$$m\angle QRS$$ = ​ (a)   $$m\angle PQS$$ = ​ (b)   $$m\angle RPS$$ = ​ (c)   $$m\angle PSQ$$ = ​ (d)  

(PQRS is a parallelogram)

Determine if the following quadrilaterals are parallelograms by using one of the listed reasons.

A parallelogram has two consecutive angles, one of which is twice the size of the other. What is the measure of the smaller angle?

Which property is not a characteristic of every parallelogram?