Answer:
13°
Step-by-step explanation:
The smallest angle in a triangle is the angle opposite the shortest side.
In this case the angle opposite side 9
let the angle be x, then using the tangent ratio in the right triangle
tan x = [tex]\frac{opposite}{adjacent}[/tex] = [tex]\frac{9}{40}[/tex] , thus
x = [tex]tan^{-1}[/tex] ([tex]\frac{9}{40}[/tex] ) ≈ 13° ( to the nearest degree )