1. **State the problem:** We have a ladder leaning against a wall forming a right-angled triangle. The ladder is the hypotenuse of length 5.2 m, and the base (distance from the wall) is 1.7 m. We need to find the acute angle $\theta$ between the ladder and the ground. 2. **Formula used:** In a right triangle, the cosine of the angle adjacent to the base is given by: $$\cos(\theta) = \frac{\text{adjacent side}}{\text{hypotenuse}}$$ 3. **Apply the formula:** Here, adjacent side = 1.7 m, hypotenuse = 5.2 m. $$\cos(\theta) = \frac{1.7}{5.2}$$ 4. **Calculate the cosine value:** $$\cos(\theta) \approx 0.3269$$ 5. **Find the angle $\theta$:** Use the inverse cosine function: $$\theta = \cos^{-1}(0.3269)$$ 6. **Evaluate the angle:** $$\theta \approx 71.0^\circ$$ 7. **Answer:** The acute angle that the ladder makes with the ground is approximately **71.0 degrees** to 1 decimal place.