Answer:
the length of side A is 2 cm
Explanation:
Hello
you can solve this by using a rule of three
According to the graph, the trapezoid must be proportional ,it means it is possible do the relationships and isolate the data we don't know
if
3 cm ⇒16.5 centimeters
Acm? ⇒11 centimeters

the length of side A is 2 cm
you can use the other length to prove
if
3 cm ⇒13.5 centimeters
Acm? ⇒9 centimeters

I hope it helps,Have a fantastic day.