初三数学视图与投影(一)(国外英文资料).doc

初三数学视图与投影(一)(国外英文资料) Lesson 12: view and projection (1) First, examination point, hot spot review Three views View: when we look at an object from a certain Angle, the object image is called a view of an object. 2. Three view drawing: we look at the same object from different directions, could see different shapes. Among them, the obtained by former backward observation object from the front view is called the main view, be in the side from left to right to observe the view of the object is called?? The left view, the view of the object from the top down, is called the top view. The three views together are called the three views. The location of the three views in the third view is the view of the top view, which is directly below the main view, and the left view is right in the main view. 4. Three view drawing of the size of the relationship between the three views as follows: the main view and top view for long, the main view and left view Gao Pingji, left view and top view equal width. The length, width and height respectively corresponding to three view drawing objects between left and right sides, between before and after, as is shown in the length between the up and down. (2) the projection Projection: the shadow that is normally used to illuminate an object with light on a plane (ground, wall, etc.) The projection of an object, called a projection, is called a projection. Parallel projection: the projection of a parallel-beam projection is a parallel projection. Central projection: the projection of light from the same point (point light) is called the center projection. Conformal projection: the projection line is perpendicular to the projection of the projection. 5. The nature of the orthographic projection: orthogonal projection of the object shape, size and its location relative to the plane. When an object of a plane parallel to the plane of the surface orthographic projection and the shape, size, the same below. Two, a typical example 1. View to see