The answer is A) 6 inches.
First I punch square root 13 in the calculator and got 3.6055... then I square the number since the formula has square root on it and got 13. Now the equation look something like this: 13 + b^2 = 49. 49 because 7^2 is 49. Then i subtract 49 by 13 and got 36. Now the equation look like this: b^2 = 36. After I square both side, I get b=6 in.
