we are given
length =20m
width =10m
Let's assume angle of inclination as theta
so, we can draw diagram
In triangle , we can see that
opposite =7
adjacent=20
now, we can use trig
[tex]tan(\theta)=\frac{7}{20}[/tex]
now, we can solve for angle
[tex]\theta=tan^{-1}(\frac{7}{20})[/tex]
[tex]\theta=19.29[/tex]..............Answer
