圆的有关知识在日常生活和工农业生产中有广泛的应用,圆是整个初中数学的一个重点和难点,是历年中考的重要考点.本文以2005年中考题为例,对和圆有关的计算题归类解析,供同学们参考.一、求圆心角例1(2005年长春市中考题)如图1,若∠BAC=35°,∠DEC=40°,则∠BOD的度数是()(A)75° Circular knowledge is widely used in daily life and industrial and agricultural production. The circle is a key and difficult point in mathematics of junior middle school. It is an important test point in the annual examination. This paper uses the 2005 exam questions as an example to calculate the circle. The classification analysis of the questions for the students to refer to. First, seeking a central angle example 1 (2005 Changchun examination questions) Figure 1, if the BAC = 35 °, ∠ DEC = 40 °, then the degree of BOD is () (A) 75°