First, fill in the blanks.

1, and the sum of the internal angles of any triangle is (180) degrees; The sum of the two acute angles of a right triangle is 90 degrees.

2. Every inner angle of a regular triangle is 60 degrees.

3. If the two angles of a triangle are 30 degrees and 40 degrees respectively, then the triangle is an (obtuse) triangle.

4. A triangle can be drawn to (3) heights.

Second, the judgment question.

1. Three line segments can definitely form a triangle. ( × )

2. At least three right triangles can be used to make one. ( × )

3. The sum of two internal angles of a triangle is 1 15 degrees, and the other angle must be 75 degrees. ( × )

4. An isosceles triangle must be an acute triangle. ( × )

5. An isosceles triangle can be a right triangle. ( √)

6. A triangle with an acute angle is an acute triangle. ( × )

7. A triangle with an obtuse angle is an obtuse triangle. ( √)

Third, multiple choice questions.

1, the base angle of an isosceles triangle is 70 degrees, so the top angle is (b).

A, 1 10 degrees b, 40 degrees c, 55 degrees.

2. All equilateral triangles are (c).

A, right triangle b, obtuse triangle c, acute triangle

3. The sum of the internal angles of the parallelogram is (c).

A, 180 degrees b, 270 degrees c, 360 degrees

2

Fill in the blanks. ( 17%)

1. Triangle has () sides, () angles and () vertices.

2, the triangle has (); The sum of the internal angles of a triangle is ().

3. Every inner angle of an equilateral triangle is () degrees.

4. The top angle of an isosceles triangle is 700, and one of its bottom angles is ().

5. The sum of the internal angles of a rectangle and a square is () degrees.

6. According to the different angles in the triangle, it can be divided into () angle, () triangle and () triangle.

7. There are at least () acute angles in the triangle.

8. The base angle of an isosceles triangle is 400 degrees, and the top angle is () degrees.

9. The sum of right angle and acute angle must be angle ().

10. Of the three angles of a triangle, one is 50 degrees and the other is 80 degrees. This triangle is both a triangle and a triangle.

1 1. Three sticks with lengths of 5 cm, 7 cm and () cm are sure to form a triangle.

Second, the judgment question. (Mark "√" for the correct graph and "×" for the incorrect graph) (8%)

1, an equilateral triangle is also called a regular triangle. ……………………………………………( )

2. An isosceles triangle can be a right triangle. ………………………………………( )

All equilateral triangles are isosceles triangles. ……………………………………( )

4. An isosceles triangle with a vertex angle of 80 degrees must be an obtuse triangle. ……………( )

5. The sum of any two sides of a triangle is greater than the third side. …………………………………( )

6. Any two identical triangles can be combined into a quadrilateral. ………………………( )

7. An acute triangle has three heights. ………………………………………………( )

8. A triangle may have two obtuse angles. …………………………………………( )

Third, calculation. (44%)

1, oral calculation. ( 12%)

0.46-0.06= 3.7+4.3= 1+0.55=

4.6- 1.8= 0.65+0.32= 10-9.9=

4+0.92= 4. 1- 1. 1= 0.05+0.5=

7.2+ 1.8= 1.7+0.37= 6.6-6=

2. Use vertical calculation. ( 18%)

26.7- 17.5= 6 1.6+3 1.9= 30- 1.65=

24.08+4.33= 67.08-7.58=

check computations

32.5+ 17.45= 45.8-22.27=

check computations

3. Use a simple method to calculate. (8%)

27.2-4.42-2.58 38.3+45.5-8.3

99×37+37 98×45

4. Calculate the degree of the angle 1 in the figure below. (6%)

Draw the height at the bottom of the picture below. (6%)

Decimal Grade Four (IV) Page 3 (* * * Page 4)

Fifth, solve the problem. (25%)

(1) It is known that the top angle of an isosceles triangle is 60 degrees. What is the base angle of this isosceles triangle? (5%)

(2) The base angle of an isosceles triangle is 60 degrees. What is its vertex angle? What else can you call a triangle? (5%)

(3) The train travels 3 12km in 3 hours, and the car travels 260km in 5 hours. How many times the speed of the train is that of the car? (5%)

(4) The school canteen bought 950 kilograms of flour, transported 3 cars and left 50 kilograms. How many kilograms does each car transport on average? (5%)

(4) The circumference of an isosceles triangle is 40 cm, and its waist is 12 cm. So, how long is its cardinal number? (5%)