So we will use trigonometry to solve this because it is a right triangle. The hypotenuse is the ladder (h) and the two smallest sides are the floor and the vertical wall (w).
That angular ladder does with the ground= A
sin A = opposite / hypotenuse
[tex]\begin{gathered} \sin \text{ A = }\frac{14.8}{15}=0.986 \\ A=\sin ^{-1}(0.986)=80.4\text{degrees} \end{gathered}[/tex]
No, the ladder will not be safe
Now let's make it safe:
The lenght of the ladder (w) is constant, so it remains 15
So now let's ask in an inequality what height will be safe (70degrees or less)
[tex]\begin{gathered} A=\sin ^{-1}(\frac{w}{15})\leq70 \\ \sin (\sin ^{-1}(\frac{w}{15}))\leq\sin (70) \\ \frac{w}{15}\leq0.9396 \\ (15)\frac{w}{15}\leq0.9396(15) \\ w\leq14.09 \end{gathered}[/tex]
What does that mean? As long as you position the ladder against the wall so that the height from the ground to the top of the ladder is <14.09 ft
