2. Method of solving the ratio: According to the basic properties of the ratio and solving the ratio, the ratio is first converted into an equation in which the product of the outer term is equal to the product of the inner term, and then the value of the unknown term is obtained by solving the equation.
3. The solution of fractional proportion: First, cross-multiply to rewrite the proportional formula into an equal product formula, and then solve the equation to find the value of the unknown item.
4. Name of each part: A: B = C: D.
External Material: Internal Material = Internal Material: External Material
5. Proportion:
The ratio of the distance on a picture to the actual distance is called the scale of this picture.
6. Distance on the map: Actual distance = The units of distance and actual distance on the scale map should be unified.
7. The meaning of solution ratio: The unknown term in the proportion is called solution ratio.
8. Classification of scale
Scale is divided into reducing scale (scale; 1); According to different forms of expression, scale can also be divided into line scale and numerical scale.
We usually contact with reducing the scale, such as maps. However, in actual production and research, sometimes because the machine parts are relatively small, it is necessary to expand the actual distance by a certain multiple before drawing on the drawings. At this time, the enlarged scale is needed, so the scale is not all less than 1.