1. Stereo graphics in life
Cylindrical, conical, cubic, cubic, prismatic sphere ... are all three-dimensional figures.
Step 2 unfold and fold
In a prism, the intersection of any two adjacent faces is called an edge, and the edges of two sides of the prism are called side edges. All sides of a prism are equal in length. The top and bottom surfaces of the prism are the same, and the sides are rectangular. Generally speaking, according to the number of sides on the bottom of the prism, the prism can be divided into three prisms, four prisms and five prisms ... P 1 1.
3. Cutting geometry
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Look at the problem from different angles
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5. Plane graphics in life
For example, triangles, circles, squares, heptagons ... are all plane figures.
chapter two
1. Why is the quantity insufficient?
Anything without a sign or+in front of it is called a positive number, which is greater than 0.
Numbers preceded by-are called negative numbers, all of which are less than 0.
0 is neither positive nor negative P39, P40.
2. Counting axis
Any rational number can be represented by a point on the number axis.
Three elements of the number axis:
1. Positive direction
2. Origin
3. Unit length
Antiquities: Two numbers are only different in sign, so one number is called the inverse of the other number, which is also called the antipodal P44 of each other.
The number represented by two points on the number axis is always larger on the right than on the left. Positive numbers are greater than 0, negative numbers are less than 0, and positive numbers are greater than negative numbers P44 45.
3. Absolute value
The distance from the origin on the axis of a number is called the absolute value of the number.
The absolute value of a positive number is itself.
The absolute value of a negative number is the opposite number.
The absolute value of 0 is 0.
4. Addition of rational numbers
The same symbols add up to positive, and different symbols add up to negative P55.
5. Rational number subtraction
Subtracting a number is equal to adding the inverse of this complaint.
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7. Changes in water level
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8. Power of rational number
P75
9. Division of rational numbers
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10. Power of rational number
P83 bottom
1 1. Mixed operation of rational numbers
Calculate the power first, then multiply and divide, and finally add and subtract. If there are brackets, count them first.
12. Computer use
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chapter three
What can letters stand for?
P 103
2. Algebraic expressions
P 106 paragraph 1, 2
3. Algebraic evaluation
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4. Merge similar projects
If there are the same letters and the indexes of the letters are the same, they are called similar items. When numbers are added and letters and letter indexes remain unchanged, it is called merging of similar items.
P 1 16
5 de-bracket
The plus sign precedes the parentheses. Remove the brackets and+,the symbol in brackets remains the same, and-comes before the brackets. Remove the brackets and-,the symbols in brackets have changed.
Explore the law
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chapter four
1. Line, ray, straight line
Line segment: two endpoints, which cannot extend indefinitely.
Ray: It has an endpoint and can extend to one end indefinitely.
Straight line: it has no end points and can extend to both ends indefinitely.
Only one straight line passes through two points.
2. Compare the lengths of line segments
P 139
3. Degree and expression of angle
An angle consists of two rays with a common endpoint, and the common endpoint of the two rays is the vertex of the angle.
An angle can be regarded as a ray rotating around its endpoint.
4. Angle comparison
P 149
parallel
Use || to indicate parallelism.
After passing a point outside the straight line, there is one and only one straight line parallel to this straight line.
If both lines are parallel to the third line, then the two lines are parallel to each other.
6. vertical
P 157
On the plane, there is one and only one straight line perpendicular to the known straight line at a point.
Of all the line segments connecting points outside the straight line and points on the straight line, the shortest vertical line is P 158.
7. Interesting jigsaw puzzle
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chapter five
1. How old are you this year?
P 167 169
2. Solve the equation
P 177
3. Equations in the calendar
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4. I'm getting fat
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Discount sale
Profit = selling price-cost
Profit rate = profit/cost
6. Hope Project Charity Performance
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7. Can you catch up with Xiaoming?
Downstream velocity = still water velocity+current velocity
Backward speed = still water speed-water flow speed
8. Education savings
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Chapter vi
1. Think about it 1 ten thousand.
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2. Scientific symbols
P20 1 or more words
3. Fan chart
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4. Do you have confidence?
The percentage of each part in the whole is equal to the ratio of the degree of the central angle of the sector corresponding to this part to 360 degrees.
Selection of statistical charts
Column: clearly indicate the specific quantity of each item.
Broken line: clearly reflect the changes of things.
Sector: clearly shows the percentage of each part in the whole.
Chapter VII
1. Can you touch the red ball?
Deterministic events are divided into inevitable events and impossible events, and uncertain events are called uncertain events.
2. Roulette game
The greater the percentage in the circular turntable, the greater the possibility that the pointer will fall.
3. Who turned four digits?
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It took me an hour and a half to type ~ ~
Learn to refuel! ! !