The vertical height of the triangle. Horizontal width refers to the length of BC or B'C'. It is the length of the side perpendicular to the height-usually called the horizontal width in civil engineering. It's actually a horizontal length.

Vertical height: the ordinate distance of the moving point. Horizontal width: the distance between the horizontal coordinates of two fixed points.

Divide the triangle into two parts along the horizontal direction. Upper area = horizontal width× h/kloc-0 /×1/2, lower area = horizontal width× H2×1/2, and h 1+h2= vertical height. The conclusion has been proved.

Extended data:

1. If three sides of a triangle are proportional to three sides of another triangle, then the two triangles are similar (abbreviated as: two triangles with three sides corresponding to a ratio are similar).

2. If two sides of a triangle are proportional to two sides of another triangle and the included angles are equal, then the two triangles are similar (abbreviated as: triangles with two proportional sides and equal included angles are similar).

3. If two angles of a triangle correspond to two angles of another triangle, then the two triangles are similar (referred to as two triangles with equal angles are similar for short).

4. If the hypotenuse and right-angled side of a right-angled triangle are proportional to the hypotenuse and right-angled side of another right-angled triangle, then the two triangles are similar.

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