Answer 9.75 ft
Reason
Using the Pythagorean theory,
a^2 + b^2 = c^2 (the hypotenuse)
Since we know the diagonal measurement (the hypotenuse) we will call c=12
We know one leg is 7, so we will call b=7
Now we will solve for “a”
Changing the equation to subtract
c^2 - b^2 = a^2
Substitute in our numbers
12^2 - 7^2 = a^2
144-49= a^2
95 = a^2
Take square root of both sides
9.746 = “a” the unknown length
Round to nearest hundredth
9.75