2. Definition: Generally, the ratio of the vertical height h to the horizontal width l of a slope is called the slope, that is, the tan a value (A is the included angle between the slope and the horizontal plane).
3. Slope is the steepness of the surface element. Generally, the ratio of the vertical height h to the horizontal distance l of a slope is called the slope (or the slope ratio), which is represented by the letter I, that is, the tangent value of the slope angle (i=tan slope angle =h:l).
4. Representation method: There are four methods to represent slope: percentage method, degree method, density method and fraction method, among which percentage method and degree method are commonly used.