The area formula of trapezoid is (upper bottom+lower bottom) × height ÷2, and the letter S=(a+b)×h÷2. Formulas are usually an important part of solving mathematical problems. Remembering formulas can facilitate solving problems and greatly reduce workload and working hours. One formula can solve a class of problems. The upper and lower bottoms of the trapezoid are parallel. The line connecting the midpoints of the two waists of the trapezoid midline is called the midline parallel to the two bottoms, which is equal to half of the sum of the upper and lower bottoms.

The concept of trapezoid refers to a set of quadrilaterals whose opposite sides are parallel and the other set of opposite sides are not parallel. Two parallel sides are called the bottom of a trapezoid, in which the long side is called the bottom and the short side is called the bottom. You can also simply think that the upper part is called the upper bottom and the lower part is called the lower bottom. Non-parallel edges are called waists. The vertical section sandwiched between the two base sides is called the height of the trapezoid. A trapezoid whose waist is perpendicular to the bottom is called a right-angled trapezoid. Isosceles trapezoid, called isosceles trapezoid, is a special trapezoid, and its judgment method is similar to isosceles triangle.