Figure 2:

Extended data:

Proportion is a general term in technical drawing, which refers to the ratio between the linear size of a figure and its physical counterpart. Two formulas with equal ratios are called ratios, such as 3: 4 = 9: 12 and 7: 9 = 2 1: 27.

In 3: 4 = 9: 12, 3 and 12 are called external proportional terms, and 4 and 9 are called internal proportional terms. None of the four digits of the ratio can be 0.

There are four items in the proportion, namely two internal items and two external items; In 7: 9 = 2 1: 27, 7 and 27 are called external proportional terms, and 9 and 2 1 are called internal proportional terms.

There are four items in the proportion, namely two internal items and two external items.

If the lengths of two line segments AB and CD are measured by the same length unit, which are M and N respectively, then the ratio of these two line segments is the ratio of their lengths, that is, AB:CD=m:n, where the line segments AB and CD are called the first and last terms of this line segment ratio respectively. If M: N is expressed as the ratio k, then AB: CD = K, or AB = K CD. The ratio of two line segments is actually the ratio of two numbers.

Baidu encyclopedia-proportional line segment

Baidu encyclopedia-trapezoid