Answer:
Assuming you're rounding to the nearest tenth, he should cut the brace 4.5 feet long.
Explanation:
Since this is a right triangle, you can use the a^2 + b^2 = c^2 easily.
You can use either 2 or 4 as the a or the b.
After filling in the equation, 2^2 + 4^2 = c^2, you can calculate it to find it is 4 + 16 = c^2.
If you add 16 + 4, you get 20. So now, you need to find the square root of 20 which is 4.4721 but if you round to the nearest tenth, you get 4.5^2.
He should cut the brace to 4.5 square feet.
I hope this helps :))