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近年中考中的阴影部分面积问题,已不再是课本中的常规题型一统天下了,而出现了许许多多的以其他知识为背景的题型,为此我们以近年各地中考题为例说明,供同学们学习时参考。一、与函数图象牵手例1(2013·白银中考)如右图,⊙O的圆心在定角∠α(0°<α<180°)的角平分线上运动,且⊙O与∠α的两边相切,图中阴影部分的面积S关于⊙O的半径r(r>0)变化的函数图象大致是()分析:连接OB、OC、OA,求出∠BOC的度数,求出AB、AC的长,求出四边形OBAC和扇形OBC的面积,即可求出答案。
In recent years, the area of the shaded area in the middle school entrance examinations is no longer the usual type in the textbooks. Instead, there have been many kinds of questions with other knowledge as the background. Therefore, taking the examination questions in various places in recent years as an example , For students to learn reference. In the right figure, the center of ⊙O moves at an angle bisector of angle ∠α (0 ° <α <180 °), and ⊙O and ∠α The area of the shaded area in the figure is a function image of the change of the radius r (r> 0) of ⊙O roughly. () Analysis: Connect OB, OC, OA and find the degree of ∠BOC, AB, AC long, find the quadrilateral OBAC and sector OBC area, you can find the answer.