If a pentagon is regular, then all of the sides are the same length. This means that

So, if
, the lengths of the sides evaluate to

So, all the sides of the pentagon are 21 units long, and AB is 21 units long as well, because all sides are the same length.
1/4 because you just divde the numerator and the denominator by 12
Answer:
86
Step-by-step explanation:
i dont really kbow why but i think it 86