we have

Complete the square. Remember to balance the equation by adding the same constants to each side


Rewrite as perfect squares


therefore
the answer is

The next value would be 48. The values keep increasing by odd numbers. Like the first one is 3 then it goes to 5.
3, 5, 7, 9, 11, 13.....
Step-by-step explanation:
Recall the Ratio for tan
Tan(theta) = opposite / adjacent
Tan (x) = 9 / 5
solve for x (use Tan^-1(...) )
The answer is 28 sq. Units