足球运动员总是选择张角比较大一点的位置射门,这样比较容易把球射进球门.如右图,设AB是球门,一球员沿直线l带球逼近球门,试问在直线l上何处射门,张角最大?分析设直线l上的M点对球门AB张角最大.再设N为直线l上非M的任一点,则N对AB的张角β必小于M对球门AB的张角α.不难证明,圆 The football player always chooses a position where the opening angle is relatively large, so it is easier to shoot the ball to the goal. As shown in the figure on the right, AB is the goal. A player approaches the goal with a straight ball and asks where on the line l. The maximum angle of the shot, the angle of the open angle analysis set the M point on the straight line l to the maximum angle of the goal AB. Let N be any point other than M on the straight line l, then the opening angle β of the N pair AB must be smaller than the opening angle of the AB goal. Angle α. Not difficult to prove, round