For a given velocity of projection from a point on the inclined plane, the maximum range down the plane is three times the maximum range up the incline. Then find the angle of inclination of the inclined plane.

Explanation

To solve the problem, we need to find the angle of inclination of the inclined plane given that the maximum range down the plane is three times the maximum range up the incline.

### Step-by-Step Solution:

1. **Understanding the Problem**:
- Let \( R_1 \) be the maximum range up the incline.
- Let \( R_2 \) be the maximum range down the incline.
- According to the problem, \( R_2 = 3 R_1 \).
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