Three-dimensional figure: prism, pyramid, cylinder, cone, sphere, etc.
1, geometry
Plane graphics: triangle, quadrilateral, circle, etc.
Front view-from the front.
2. Three views of geometry (left and right)-viewed from the left (right) side.
Top view-from above.
(1) will judge three views of a simple object (straight prism, cylinder, cone and ball).
(2) can describe the basic geometric or physical prototype according to the three views.
3, the three-dimensional graphic plane expansion diagram
(1) The same three-dimensional figure is unfolded in different ways, and the plane figure obtained is also different.
(2) Understand the plane development diagrams of straight prisms, cylinders and cones, and judge and make three-dimensional models according to the development diagrams.
4. Points, lines, surfaces and bodies
Synthesis of (1) Geometry
Point: the intersection of straight lines is the point, which is the most basic figure of geometric figures.
Line: The intersection line between faces is a line, which can be divided into straight lines and curves.
Face: Surrounding the body is a face, which is divided into plane and curved surface.
Volume: Geometry is also called volume for short.
(2) Points move into lines, lines move into planes, and planes move into adults.
(2) Lines, rays and line segments
1, basic concept
Graphic straight ray line segment
There are no two endpoints.
Represents a straight line a
AB line segment a of straight AB(BA) ray
AB line (BA)
Practice is described as a straight line ab;
Let straight line a be ray AB and line segment a;
Making line segment ab;
Connecting AB
Prolonging narration cannot prolong the extension line AB of the reverse extension line AB;
Reverse extension line segment BA
2, the nature of the line
There is a straight line after two o'clock, and there is only one straight line.
To put it simply: two points determine a straight line.
3. Draw a line segment equal to the known line segment.
(1) metric method
(2) Drawing with a ruler and a ruler
4, the size of the line comparison method
(1) metric method
(2) Overlapping method
5. The midpoint (bisector), bisector, quadrant, etc. of a line segment.
Definition: the point that divides a line segment into two equal lines.
Graphics:
college of business administration
Symbol: If point M is the midpoint of line segment AB, then AM=BM=AB, AB=2AM=2BM.
6, the nature of the line segment
Among the connecting lines between two points, the line segment is the shortest. Simply put, the line segment between two points is the shortest.
7. Distance between two points
The length of the line segment connecting two points is called the distance between two points.
8. Location of points and straight lines.
(1) point is on a straight line (2) point is outside the straight line.
(3) Angle
1, angle: A figure composed of two rays at a common endpoint is called an angle.
2, the angle of representation (4):
3. Angle measurement unit and conversion
4. Classification of angles
Acute angle, right angle, oblique angle and fillet
Range 090=90 90 = 180=360
5. Angle comparison method
(1) metric method
(2) Overlapping method
6. Approximation of sum, difference, time, point and its angle
7. Draw an angle equal to the known angle.
(1) With the help of a triangular ruler, you can draw a multiple of 15, and between 0 and 180, * * can draw an angle of 1 1.
(2) With the help of protractor, the angle of a given degree can be drawn.
(3) Draw with a ruler.
8. The horizontal line of the corner
Definition: Starting from the vertex of an angle, the ray that divides this angle into two equal angles is called the bisector of this angle.
Graphics:
Symbol:
9. Complementarity and complementarity
(1) If 2=90, 1 and 2 are complementary angles, where 1 is the complementary angle of 2 and 2 is the complementary angle of 1.
(2) If 2= 180, then 1 and 2 are complementary angles, where 1 is the complementary angle of 2 and 2 is the complementary angle of 1.
(3) The nature of complementary angles: the complementary angles of equal angles are equal.
10, direction angle
(1) positive direction
(2) North (South) East (West) direction
(3) East (West) North (South) direction