x is the ladder ,x =36
y is the distance between ladder and wall y=12
z is the wall
we have in this triangle , only the hypotenuse(x) and the adjacent side
so,'
[tex]\cos \theta=\frac{y}{x}=\frac{12}{36}=0.33[/tex][tex]\theta=\cos ^{-1}(0.33)[/tex][tex]\theta=70\circ(approximately)[/tex]