(1) The center line of the trapezoid is parallel to the two bottoms, which is equal to half the sum of the two bottoms.

(2) Two times the height of the bit line in the trapezoid divided by two equals the area of the trapezoid, which is represented by the symbol L..

The trapezium midline theorem is a theorem of geometry, which means that the line segment connecting the midpoints of the two waists of the trapezium is called trapezium midline, and the trapezium midline is parallel to the two bottoms, which is equal to half the sum of the two bottoms.

Common auxiliary line

1, left height (determined according to the actual topic).

2. Translate a waist.

3. Translate the diagonal.

4. Stretch your waist at a point in the opposite direction.

5. Take the midpoint of one waist and connect the two ends of the other waist.

6. Take the midpoint of the two bottoms and draw a parallel line between the two waists through the midpoint of the bottoms.

7, take two waist midpoint, attachment, as the center line.