Answer: 8.1ft
Explanation:
It may help to draw it out but for this question you would have to use pythagoras' theorem.
The formula for the shorter side is a²=c²-b²
The height of this triangle is 4ft (b) and the hypotenuse (the diagonal that stretches from the top to the bottom) is 9ft (c).
When we put the numbers in the formula you get a²=9²-4²
9²=81
4²=16
a²=81-16
a²=65
Then because we want to find a on it's own you would have to square root 65 which is 8.1 (to the nearest tenth)