Answer:
The ladder is 5.1 m and it is leaning against a wall.
The wall is perpendicular to the ground.
This means the ground forms 90 degrees with the wall.
This situation forms a right angle triangle.
Therefore, the acute angle the ladder forms with the ground can be found as follows:
Using trigonometric ratios,
cos ∅ = adjacent / hypotenuse
where
∅ = acute angle
Therefore,
adjacent side = 1.8 m
hypotenuse side = 5.1 m
Hence,
cos ∅ = 1.8 / 5.1
∅ = cos⁻¹ 0.35294117647
∅ = 69.3326835065
∅ = 69.3°
Therefore, the acute angle the ladder makes with the ground is 69.3 degrees.