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对几何图形角的种类,小学数学教材只编入了直角、锐角,钝角、平角和周角,而对大于180°而小于360°的角是什么角?教材未作介绍。因此,有的教师在遇到学生提出类似问题时,便产生了疑难。例如,在计算如图扇形面积时,有学生提出230°的角是什么角?有的教师只是含糊其辞,无法圆满地回答学生的发问;有的则为了使学生在心理上得到满
For the types of geometric figures, primary school mathematics textbooks include only right angles, acute angles, obtuse angles, flat angles and perimeter angles, and what angles are those angles greater than 180 ° and less than 360 °? The teaching materials are not introduced. Therefore, some teachers have encountered difficulties when they come up with similar problems raised by students. For example, when calculating the fan-shaped area as shown in the figure, what angle is the angle at which the student proposes a 230 ° angle? Some teachers simply vaguely fail to answer students' questions satisfactorily. Others, in order to make students psychologically satisfied