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手电筒、探照灯以及聚光式太阳灶,都有一个抛物面型反射镜。这抛物面是由抛物线4OB绕Z轴旋转而成的。见图1。土建工程中,也能见到抛物线拱的渡槽、桥梁等。下面介绍抛物线的简易作图法。1.作矩形4BCD。
Flashlights, searchlights, and spotlight solar cookers all have a parabolic reflector. This parabola is made by rotating the parabola 4OB around the Z axis. see picture 1. Civil engineering works can also see the aqueducts and bridges of parabolic arches. The simple parabolic drawing method is described below. 1. Make a rectangle 4BCD.