A finite segment cut from a straight line is called a line segment, which is usually represented by two endpoints, such as line segment AB. When a line segment starts from a fixed point and moves in a certain direction, the trajectory formed is a ray, and the ray leads from a point to a graph composed of two rays, which is called an angle. This point is called the vertex of the angle, and both sides of each ray of the angle called the angle form a straight line. Such angles are called right angles, and each right angle is 10.
An angle less than 90 degrees is called an acute angle. An angle greater than 90 degrees and less than 180 degrees is called obtuse angle. The obtuse angle at which the serpentine rotates around the endpoint is called fillet. The fillet is 360 degrees. Fillets are used to indicate the size of angles. When two lines intersect at right angles, they are said to be perpendicular to each other. One of the straight lines is called the perpendicular of the other straight line, and their intersection point is called the vertical foot.
Two straight lines that do not intersect on the same plane are called parallel lines. The length of a parallel line connecting two line segments is called the distance between two points. The distance between two points is the length of the vertical line segment from a point outside the line to the line. The distance from a point to a line is the distance from any point in two parallel lines to the other line. The distance between parallel lines is a closed figure surrounded by three line segments, which is called triangle.
A triangle with three internal angles all acute. An acute triangle has a triangle with a right angle inside. Two sides with right angles are called right angles, and the side opposite to right angles is called hypotenuse. A right triangle with an obtuse angle is called an isosceles triangle with two equal sides, the other side is called a waist, and the angle between the two waists is called a vertex. The two corners of the bottom are called two isosceles triangles with equal right angles.
A triangle with three equal sides is a regular triangle, also called an equilateral triangle with three unequal sides. The sum of the three internal angles of an equilateral triangle is called the sum of the internal angles of the triangle, and the sum of the internal angles of the triangle is 180 degrees. If a figure is folded in half along a straight line, the parts on both sides of the straight line can overlap each other. This figure is called a line symmetric figure. If the axisymmetric figure rotates the figure 65438+ around the fixed point,
Two groups of parallelograms with parallel opposite sides. The four corners of a parallelogram are right angles. A rectangle with equal length and width, a rectangular square with equal adjacent sides, a parallelogram diamond, and the sum of the lengths around a plane figure. girth
There is only one set of quadrilateral trapeziums with parallel opposite sides, two isosceles trapeziums with equal waist, and only one trapezoid with waist perpendicular to the bottom. When a line segment travels around its fixed end on a plane and draws a closed curve called a circle, the fixed end of the line segment is called the center of the circle.
The radius of the line segment from the center of the circle to any point on the circle. Two circles with the same radius have the same center, and two concentric circles with different radii pass through the center of the circle and both ends are on the circumference of a closed curve on the diameter circle of the line segment on the circle.
Refers to the length of a circle. The ratio of the circumference to the diameter of a circle is called pi, which is expressed by the Greek letter π, that is, π = the circumference of a circle ≈ the diameter of a circle ≈3. 14 1592653589 ... In elementary school mathematics, the approximate value of pi is often taken, that is, π≈3. 14. The inner circle is called the inner ring and its diameter is called the inner diameter. In a cylinder, two parallel faces are called the bottom surface. For example, cuboids, cubes and cylinders all have two bottom surfaces. Except for the two bottom faces, all the other faces of the cylinder are side faces.
The surface of an object is the surface of an object. For example, the six faces of a cuboid are the faces of a cuboid. The intersection of two surfaces in an object is called an edge. The plane cuts the object from the direction perpendicular to the object. The cutting plane is called a hexahedron, and its cross section is surrounded by six rectangles (or two opposite surfaces may be squares). The three sides that intersect at a point are called length, width and height respectively. This intersection is called the fixed point of a cuboid.
A rectangle with a Zhou Suocheng around its side is called a cylinder, and a right triangle simply rotates around a right side. Zhou Suocheng geometry is called a cone, and the sum of the outer surface areas of an object or three-dimensional figure is called the surface area of the object or three-dimensional figure. It includes two opposite faces, namely, the side face area and the bottom face area. These two faces are congruent and parallel, and all other faces are parallel to a certain straight line. Each vertex of a polyhedron is connected to a point outside the plane containing the polygon.
A straight line of a plane figure on the same plane rotates once as an axis, and the resulting solid is called a rotating body. This straight line is called the axis of rotation. For example, cylinders, cones, frustums, spheres and hemispheres are all rotating bodies. A solid surrounded by equidistant points in a certain space is called the angle of a sphere with the center as the vertex and two radii, and the angle surrounded by two adjacent sides of a central angle is called the sum of all internal angles of an internal polygon.
When Figure A and Figure B are similar figures, if the length of each side of Figure A is twice that of Figure B, we say that Figure B is a 1/2 thumbnail of Figure A. When Figure A and Figure B are similar figures, if the length of each side of Figure A is twice that of Figure B, we say that Figure A is the superposition of the corresponding angles of two enlarged figures of Figure B, and the corresponding side lengths of two similar figures are overlapped in a certain proportion.
A table containing only one statistical item. For example, a single statistical table containing two or more statistical items is called a composite statistical table or a composite statistical table. For example, the number of boys and girls in each grade of Xiyuan Primary School in Hefei is used to express the interrelated quantitative relationship. Graphical statistical charts represent a certain quantity by unit length. Draw straight lines with different lengths according to numbers, and then arrange these straight lines in a certain order, which is called bar chart, also called bar chart. Bar chart is a statistical chart. In the histogram, there is no gap between columns, and the group spacing is continuous. bar chart
Use unit length to represent a number, trace each point according to the number, and then connect these points in turn with line segments. Such a statistical chart is called a line chart. For example, the stock price fluctuation line chart shows the total with the area of the whole circle, and the sector area of the circle shows the percentage of the total. Such a statistical chart is called a sector statistical chart (also known as a circle chart). When two numbers are added, the addend positions are interchanged, and the sum remains unchanged. Called additive commutative law. Or always add the last two numbers first, and then add the first number, and their sum remains the same. This is the so-called law of addition and association. Example: (3+4)+5=3+(4+5) Addition and associative law multiply two numbers and exchange the positions of two factors. Their products are unchanged, which is called multiplication and substitution law, for example, 5×3=3×5.
Multiply three numbers, the first two numbers are multiplied by the third number, or the last two numbers are multiplied by the first number, and the product remains unchanged. This is the so-called law of multiplication and association. For example, the law of multiplicative association: (3×4)×5=3×(4×5) Multiplies the sum of two numbers by a number, and then multiplies the two addends by this number respectively. For example: (3+4)×5=3×5+4×5 Multiplication and division omits the mantissa after a bit of 1 to get an approximate value, depending on the number in the highest mantissa. If the mantissa of the highest bit is 4 or more, all mantissas (four rounds) are discarded; If the digit on the highest digit of the mantissa is 5 or more, after the mantissa is truncated, you should enter 1 (five digits) before it. This method of finding the divisor is called rounding. When calculating the divisor, all the digits after a number are truncated. No matter what the highest digit of the truncated part is, you should enter 1 at the last digit of the reserved part, which is called rounding method.
When buying and selling goods, sometimes because of packaging fees, postage, freight and other expenses, or because of price increases, the actual price plus its expenses is called price increase, which means that the actual price is a few percent of the fixed price and is called discount. For example, 20% off (80%), 15% off (85%), 50% off and 20% off (that is, 15% off and then 15% off) will become 64. Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra Algebra.
Algebraic expressions without addition or subtraction are called monomials. The letters in the algebraic expression are replaced by numerical values, and the calculated result is called the algebraic value. For example, when a=5, b=7, and algebraic expression 2a+6b=52, the numerical factor in numerical monomials is called the algebraic sum of several monomials, and it is called a formula in which two algebraic expressions are connected by polynomials.
An equation with unknowns is called the process of solving equations. When solving an equation, the unknowns in the problem are represented by a letter. After the unknown is set, the equations are listed according to the equivalence relation in the problem, which is called Brillouin equation.
Turning a polynomial into the product of several polynomials is called factorization. Factorization arranges chess pieces or people into squares and rectangles, which is called a square matrix. According to the arrangement, it is usually divided into solid square matrix and hollow square matrix. When the square matrix is cut parallel to the bottom surface of the cone, the section from the bottom surface to the bottom surface is called truncated cone. When the two bottom surfaces of a frustum are circles parallel to the bottom surface to cut off the pyramid, the ratio of the cross-sectional area to the bottom surface is more than three times, and the ratio of the two sections is connected together.
When the number of digits of a number is 0, 2, 4, 6 and 8, the number is divisible by 2, and when the sum of digits of a number is divisible by 3, the number is divisible by 3. For example:
The sum of the digits of 345 is 3+4+5 = 12, and 12 is divisible by 3.
So 345 can be divisible by 3, and the last two digits of an integer are multiples of 0 or 4. This number is also a multiple of 4. It can be said that even numbers are even after being divided, which is a multiple of 4, such as:
The last two digits of 23876 are 76, which is a multiple of 4, so 23876 is a multiple of 4. One digit of an integer is 0 or 5.
This number is a multiple of 5. The sum of all the numbers of an even number is a multiple of 3, and this number must be a multiple of 6. For example:
576 is an even number, and the sum of numbers 5+7+6= 18 is a multiple of 3.
So 576 is a multiple of 6, a multiple of 6.
An integer, after its last bit is crossed out, subtracts twice the last bit crossed out from the remainder. If the number is a multiple of 0 or 7, it is a multiple of 7. (If the quantity is still large, you can repeat the above method. ) The last three digits of an integer are multiples of 0 or 8, and this number is multiples of 8, for example:
Both 38960 and 67000 are multiples of 8. The sum of all digits of an integer is a multiple of 9, and this number is a multiple of 9, for example:
4896,4+8+9+6=27,
27 is a multiple of 9,
So 4896 is a multiple of 9. The last digit of an integer is 0, which is a multiple of 10. In an integer, if the difference between the sum of odd numbers and the sum of even numbers is 0 or a multiple of 1 11.40000000006.
A point has only position, no length, no size and cannot be separated. A dotted line has no end points and can extend infinitely in two directions. An unmeasurable linear ray has only one endpoint, and the other end can extend indefinitely. The unmeasurable ray segment has two endpoints and a certain length, so it can be measured. In all the straight lines connecting two points, the shortest line segment of the line segment is in the same plane, and two mutually perpendicular straight lines intersect to form four angles, and each angle is an angle.
The distance between two parallel lines is equal everywhere. The angle of parallel lines is related to the size of both sides of the angle. The greater the angle, the greater the angle. Two groups of opposite sides of an angular rectangle are parallel and equal respectively. The four corners are right angles, and the diagonal lines are equal in length. It is an axisymmetric figure and a point symmetric figure. Rectangular square is a special rectangle, except for its rectangular characteristics, its four sides are equal. Its two diagonal lines are perpendicular to each other and equally divided. The two opposite sides of a square diamond are parallel and equal, and the four sides are equal in length. Their diagonals are perpendicular to each other and equally divided, but their lengths are not equal. They belong to an axisymmetrical figure and a point symmetrical figure diamond.
The two opposite sides of a parallelogram are parallel and equal, the two diagonals are equal, and the diagonals are equally divided, which belongs to a point symmetrical figure. A parallelogram triangle has three angles, three sides and three vertices, and the sum of the three internal angles is 180 degrees. One angle of a right triangle is a right angle, and the sum of the other two acute angles is 90 degrees, and the two right angles are perpendicular to each other. The two waists of an isosceles triangle are equal and the two base angles are equal. It belongs to an axisymmetric figure. The height on the base is an isosceles triangle of symmetry axis. An isosceles triangle has the characteristics of a right triangle and an isosceles triangle, and there are two isosceles right triangles with a base angle equal to 45 degrees.
Three sides of a regular triangle are equal, and three internal angles are equal, all equal to 60 degrees. An equilateral triangle is an axisymmetric figure, and the height of three sides means that the midline of a symmetrical trapezoid is parallel to the two bottoms (namely, the upper bottom and the lower bottom), which is equal to half the sum of the two bottoms. In addition to the characteristics of a general trapezoid, an isosceles trapezoid has two equal waists, with two equal upper and lower bottom angles, which belong to an axisymmetric figure. The connecting line between the midpoint of the upper bottom surface and the midpoint of the lower bottom surface is an isosceles trapezoid with symmetry axis. In the same circle, all radii are equal and all diameters are equal, which is equal to twice the radius. This is a symmetrical figure. When the diameter is symmetrical, it is also a point symmetrical figure, and the center of the circle is the center of symmetry. A circular cuboid has six faces, all of which are rectangles (or two opposite faces are squares), and the areas of the opposite faces are equal, with 65438.
A cube is a special cuboid, its six faces are all squares, its six faces are all equal in area, and its 12 sides are all equal in length. The upper and lower bottom surfaces of a cubic cylinder are two circles with equal areas, and the lateral expansion of the cylinder is a rectangle, the length of which is equal to the circumference of the bottom surface of the cylinder, and the width is equal to the height of the cylinder cone. The line segment from the fixed point of the cone to the center of the bottom is perpendicular to the bottom, and the lateral expansion of the cone is a circle.