Simple....
assuming you have studied Pythagorean Theorem...
\(a^{2} + b^{2} = c^{2}\)
If it leans 12 ft...then c=12
the base is at 3 ft or b=3
You need to find a....
\(a^{2}+ 3^{2} = 12^{2}\)
\(a^{2} +9=144\)
-9 -9
\(a^{2} =135\)
Square root.....
\(\sqrt{135} =11.6\)
You are measuring to the nearest tenth.
Thus, your answer....11.6 ft.
