【原】Bilingual Mathematics Teaching（4）Circles and Sectors

Words and Expressions

53	圆	circle
54	圆心	the center of a circle
55	半径	radius
56	直径	diameter
57	圆周长	circumference of a circle
58	圆周率	circumference ratio
59	弧	arc
60	圆心角	central angle
61	圆周角	angle at the circumference
62	圆规	compass
63	圆的面积	area of circle
64	扇形	sector
65	扇形统计图	sector diagram
66	圆环	circular ring

Examples

1、The circumference ratio is an infinite non-repeating decimal. It approximately equals 3.14.

圆周率是一个无限不循环小数，近似等于3.14.

2、The area of the circular ring is the difference of the areas of the inner circle and the outer circle.

圆环的面积等于内外两个圆面积之差。

3、When the radius is fixed，the area of the sector increases when its central angle increases.

半径一定时，扇形的面积随圆心角的增大而增大。

4、In a sector diagram, the circle means the whole and the sectors mean different parts in the whole. The size of the sector shows its percentage in the whole.

在扇形统计图中，圆代表总体，扇形代表总体中的不同部分，扇形的大小反应了部分占总体的百分比。

5、The size of plane covered by a circle is the area of the circle.

圆所占平面的大小叫做圆的面积。