Induction of mathematical knowledge points in the first volume of the second grade of primary school
Dynamic definition of 1. angle
The figure formed by the rotation of light from one position to another around its endpoint is called an angle. The endpoint of the rotated ray is called the vertex of the angle, the ray at the starting position is called the starting edge of the angle, and the ray at the ending position is called the ending edge of the angle.
2. Type of horn
The size of the angle has nothing to do with the length of the side; The size of an angle depends on the degree to which both sides of the angle are open. The bigger the opening, the bigger the angle. Conversely, the smaller the opening, the smaller the angle. In dynamic definition, it depends on the direction and angle of rotation. Angles can be divided into acute angle, right angle, obtuse angle, right angle, rounded corner, negative angle, positive angle, upper angle, lower angle and 0 angle, which are 10 respectively. An angle measuring system in degrees, minutes and seconds is called an angle system. In addition, there are secret system, arc system and so on.
Acute angle: An angle greater than 0 and less than 90 is called an acute angle.
Right angle: An angle equal to 90 is called a right angle.
Oblique angle: an angle greater than 90 and less than180 is called obtuse angle.
Negative angle: the angle formed by clockwise rotation is called negative angle.
Positive angle: the angle of counterclockwise rotation is positive angle.
Angle 0: An angle equal to zero.
Complementary angle and complementary angle: if the sum of two angles is 90, it is complementary angle, and if the sum of two angles is180, it is complementary angle. The complementary angles of equal angles are equal, and the complementary angles of equal angles are equal.
Inverse vertex angle: When two straight lines intersect, there is only one common vertex, and both sides of the two corners are opposite extension lines. These two angles are called antipodal angles. Two straight lines intersect to form two pairs of vertex angles. The two opposite angles are equal.
There are also many kinds of angle relationships, such as internal dislocation angle, congruent angle and internal angle of the same side (in the three-line octagon, it is mainly used to judge parallelism)!
3. Multiplication algorithm
Integer multiplication meets the following requirements: exchange law, association law, distribution law and elimination law.
With the development of mathematics, the object of operation has developed from integer to more general group.
Multiplicative commutative law: a×b=b×a
Law of multiplicative association: (a×b)×c=a×(b×c)
Multiplication and distribution law: (a+b)×c=a×c+b×c
A complete set of formulas for second-grade mathematics knowledge points
1, the perimeter of the rectangle = (length+width) ×2C=(a+b)×2.
2. The circumference of a square = side length ×4C=4a.
3. Area of rectangle = length× width S=ab
4. Area of a square = side length × side length S = a ... a = a.
5. Area of triangle = base × height ÷2S=ah÷2.
6. parallelogram area = bottom x height S=ah
7. trapezoidal area = (upper bottom+lower bottom) × height ÷2S=(a+b)h÷2.
8. Diameter = Radius× 2D = 2r Radius = Diameter ÷2r=d÷2
9. The circumference of a circle = π× diameter = π× radius× 2c = π d = 2π r.
10, circular area = pi × radius× radius? =πr
1 1, the surface area of a cuboid = (length× width+length× height+width× height) × 2.
12, cuboid volume = length× width× height V=abh.
13, the surface area of the cube = side length × side length× 6s = 6a.
14, volume of cube = side length × side length × side length v = a.a.a = a.
15, lateral area of cylinder = circumference of bottom circle × height S=ch.
16, surface area of cylinder = upper and lower bottom area+side area.
s = 2πr+2πRH = 2π(d÷2)+2π(d÷2)h = 2π(c÷2÷π)+Ch
17, cylinder volume = bottom area × height V=Sh
V=πrh=π(d÷2)h=π(C÷2÷π)h
Mathematics knowledge points and exercises in the second volume of the second grade of primary school
Knowledge points:
1, axisymmetric figure: folded in half along a straight line, with both sides completely coincident. The figure that can completely overlap after being folded in half is an axisymmetric figure, and the straight line where the crease is located is called the axis of symmetry.
2. Translation: When an object moves horizontally or vertically, and the direction of the object remains the same, this movement is translation. Only graphics with the same shape, size and direction can overlap each other through translation.
3. Rotation: The phenomenon that an object moves in a circle around a certain point or an axis is rotation.
Exercise questions:
First, fill it out.
1. If a graph is folded in half along a straight line, the graphs on both sides can completely overlap. This graph is called () graph, and this straight line is ().
2. Rectangular has () axis of symmetry, and square has () axis of symmetry.
Xiaoming walked 3 meters ahead, which is a phenomenon.
Second, judgment.
1, a circle has countless symmetry axes. ()
Uncle Zhang is driving on a straight road, and the movement of the steering wheel is a rotating phenomenon. ()
3. All triangles are axisymmetric figures. ()
Reference answer:
First, fill it out.
1. If a graph is folded in half along a straight line, the graphs on both sides can completely overlap. Such a graph is called an (axisymmetric) graph, and this straight line is the (axis of symmetry).
2. A rectangle has (two) symmetry axes and a square has (four) symmetry axes.
Xiaoming walked 3 meters ahead, which is a phenomenon.
Second, judgment.
1, a circle has countless symmetry axes. ( √ )
Uncle Zhang is driving on a straight road, and the movement of the steering wheel is a rotating phenomenon. ( √ )
3. All triangles are axisymmetric figures. ( × )
Summarize and sort out the relevant articles on the knowledge points of mathematics in the second grade of primary school;
★ Sorting out the key knowledge of mathematics in the first volume of the second grade of primary school
★ The induction of mathematics knowledge points in the first volume of the second grade of primary school
★ Arrangement of conceptual knowledge points in the first volume of second grade mathematics
★ The arrangement and summary of the knowledge points in the second grade mathematics examination.
★ Summarize the learning methods of mathematics in the second grade of primary school.
★ Second grade mathematics knowledge points
★ Summary of Math Learning Methods and Difficulties in Grade Two
★ Summary of Knowledge Points in the Second Book of Grade Two Mathematics (2)
★ Mathematics knowledge points of senior one and senior two.
★ The arrangement of mathematics learning methods in the second grade of primary school