Answer: 196 becuase line AC is 14
Explanation:
We have one angle of 90, which means the rest of the angles are 45. (90+45+45 = 180)
This also means that the length of AC and BC are both the same
We also know that the shape is a square meaning all sides are the same
We also know the Area of the square is 196
If area is base times height and a square has the same length for the base as height, then we know the formula is A x A=196 or A^2=196. So take the reverse of 196 by square rooting it.

So, line BC equals 14
Now remember how I said Line BC and AC are the same length. Well because of that AC is also 14. Lastly, because the shape is a square all sides are 14, meaning the square from the line AC is
or 196.