Question

ABCD is a parallelogram. if AB=3x+2 and CD=4x-3 find the length of AB
20
19
17
15

Answer 1

Opposite sides of a parallelogram are congruent. Thus AB = CD.

Answer 2

I don't understand.

Answer 3

Let's see. Since opposite sides of a parallelogram are congruent and AB and CD are opposite sides, then AB = CD.

Substitution gives 3x+2=4x-3
3x-4x=-3-2
-x=-5
x=5.
Thus AB=3x+2=3(5)+2=17.

Answer 4

Can I use that formula on any similar question?

Answer 5

As long as opposite sides are given, yes.

You can also set up equality using opposite angles.

Answer 6

Thanks!

Answer 7

your welcome! :D