1, oral calculation.

1074=

2703=

1300=

324=

8070=

245=

7208=

38052=

380 1920=

52+256

37+429

4990 1

39404

2. Use vertical calculation.

1247 1

206 15

46060

54376

3. Off-mold calculation.

( 1280+ 176)7

(58+86)60

Second, I review my knowledge carefully.

1, and two groups of quadrilaterals with opposite sides () are called parallelograms. Opposite sides of parallelogram () and (), diagonal ().

2. The set of parallel opposite sides in a trapezoid is called () and () respectively, and the set of non-parallel opposite sides is called ().

3. Rectangular and square are special ().

4. When two straight lines intersect into (), they are said to be perpendicular to each other. One of them is called the other's' ().

5. The quadrangles we have learned are (), (), () and ().

Third, I judge right and wrong.

1, the base of the parallelogram has only one height. ( )

2. Both triangles and parallelograms are stable. ( )

3. On the same plane, two disjoint lines are called parallel lines. ( )

On the same plane, two straight lines are not parallel, so they must intersect. ( )

5. A set of quadrangles with parallel opposite sides is called trapezoid. ( )

Choose the correct serial number and fill it in the brackets.

1. Draw a vertical line from a point on the upper bottom to the lower bottom. The line segment between this point and the vertical foot is called trapezoid ().

① waist

② Vertical line

③ high.

④ Upper bottom

2. Two straight lines intersect. If one of the angles is a right angle, the other three angles are ().

① acute angle

② Right angle

③ obtuse angle

④ Right angle

3, isosceles trapezoid () is equal.

① Two waists

② Opposite edge

③ Upper bottom and lower bottom

④ Waist circumference and height

4, on the same plane, you can draw a straight line parallel to the known straight line ().

① 1

②2

③3

(4) countless.

5. If two straight lines A and B drawn on paper intersect with the third straight line at right angles, then these two straight lines A and B are ().

① Parallel to each other

② Intersection

③ perpendicular to each other

Fifth, solve the problem.

1. A rectangle is 25m wide and 3x long. What is the circumference and area of this rectangle?

2. The circumference of a square is 36 decimeters. How many square centimeters is its area? How many square centimeters of paper does it take to make two such squares?

Put a square with a side length of 5cm and a rectangle with a length of 7cm and a width of 5cm into a big rectangle. What is its circumference and area?