投影在现实生活中的应用(国外英文资料).docVIP

投影在实际生活中的应用(国外英文资料) The application of projection in real life Projection problem can be seen everywhere in our daily life, the answers to such questions to pay attention to distinguish nature (that is, the center projection or parallel projection problem) and the features of each projection. Example 1: figure 1 is the shadow of two buildings in four different times of the day: they are arranged in chronological order, and the correct ones are () Figure 1 A, A, and B C Analysis: the suns rays are parallel, so the projection is a parallel projection. The projection of the object is the longest, and then it gets shorter, and then it gets longer; Second, that the sun rises from the east and the direction of the projection of the object on the contrary, different height of the length of the projection of the object is not the same, high projection of the object is longer, the projection objects in figure 3. The longest, its direction is the west, so time is in the morning; The projection of the object in the picture is shorter, the direction is northwest, the sun is on the southeast side, so the time is the morning; The projection of the object in the picture is shorter, its direction is northeast, the sun is on the southwest side, so the time is afternoon. In the picture, the object is long and the direction is east, so the sun is in the west, so the time is late afternoon in the afternoon. Reflection: (1) in the parallel projection, high objects also have longer projections. (2) pay attention to the direction, such as light from the east, the projection is west; The sunlight is a special parallel light, which should be noted over time, the direction of the suns rays and the laws of its projection. Example 2: as shown in figure 2, in the evening, the little light is off on the square. The line AB said stand in the square in the figure 2 small bright, line PO said upright in the square of the light pole, point P said lighting. (1) please draw a light in the picture bel